diff --git a/Interfaces/IXFileProvider.cs b/Interfaces/IXFileProvider.cs
index cc3f315..8d279ac 100644
--- a/Interfaces/IXFileProvider.cs
+++ b/Interfaces/IXFileProvider.cs
@@ -22,6 +22,7 @@ namespace xFileService.Interfaces
     {
         //
         #region Props ...
+        IXFileTagProvider TagProvider { get; }
         IHubContext<XFileEntityHub> Hub { get; }
         IXFileRepository FileRepository { get; }
         IXStorageProvider StorageProvider { get; }
@@ -53,6 +54,72 @@ namespace xFileService.Interfaces
         Task<XQueryResult<XFileDto>> ToDtoQueryResult(XQueryResult<XFile> queryResult);
         #endregion
 
+        //
+        #region Tags ...
+        /// <summary>
+        /// Attach Tag to Specified File ...
+        /// </summary>
+        /// <param name="tag"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task TagAttach(
+            string tag, 
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+
+        /// <summary>
+        /// Detach Tag fro Specified File ...
+        /// </summary>
+        /// <param name="tag"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task TagDetach(
+            string tag, 
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+
+        /// <summary>
+        /// Attach Tags for Specified File ...
+        /// </summary>
+        /// <param name="tags"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task TagsAttach(
+            IEnumerable<string> tags, 
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+
+        /// <summary>
+        /// Detach Tags for Specified File ...
+        /// </summary>
+        /// <param name="tags"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task TagsDetach(
+            IEnumerable<string> tags, 
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+        
+        /// <summary>
+        /// Detach all Attached Tags for Specified File ...
+        /// </summary>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task TagsDetach(
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+        #endregion
+
         //
         #region Tools ...
         /// <summary>
@@ -120,6 +187,56 @@ namespace xFileService.Interfaces
         Task<XFileStreamDescriptorDto> GetFileDescriptor(string fileName);
         #endregion
 
+        //
+        #region Reference ...
+        /// <summary>
+        /// Get Reference Identifier for Specified Provider and Specified File ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        string GetIdentifier(
+            string providedFor, 
+            Guid id
+        );
+
+        /// <summary>
+        /// Check Specified File has Refernce to Provider ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <returns></returns>
+        Task<bool> IsProvidedFor(
+            string providedFor, 
+            Guid id
+        );
+
+        /// <summary>
+        /// Add Specified Reference to Specified File ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task AddReference(
+            string providedFor, 
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+
+        /// <summary>
+        /// Remove Specified Reference from Specified File ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        Task RemoveReference(
+            string providedFor, 
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        );
+        #endregion
+
         //
         #region Data Model ...
         /// <summary>
diff --git a/Models/Dtos/XFileDto.cs b/Models/Dtos/XFileDto.cs
index bdc8355..81fdbc0 100644
--- a/Models/Dtos/XFileDto.cs
+++ b/Models/Dtos/XFileDto.cs
@@ -20,7 +20,7 @@ namespace xFileService.Models.Dtos
 
         public string OwnerId { get; set; }
         public XPersonDto Owner { get; set; }
-
+        
         public IList<string> References = new List<string>();
     }
 }
\ No newline at end of file
diff --git a/Providers/XFileProvider.cs b/Providers/XFileProvider.cs
index 681d3fe..61149cd 100644
--- a/Providers/XFileProvider.cs
+++ b/Providers/XFileProvider.cs
@@ -31,6 +31,7 @@ namespace xFileService.Providers
     {
         //
         #region Props ...
+        public IXFileTagProvider TagProvider { get; }
         public IHubContext<XFileEntityHub> Hub { get; }
         public IXFileRepository FileRepository { get; }
         public IXStorageProvider StorageProvider { get; }
@@ -41,6 +42,7 @@ namespace xFileService.Providers
         //
         #region Constructor ...
         public XFileProvider(
+            IXFileTagProvider tagProvider,
             IXFileRepository fileRepository,
             IXStorageProvider storageProvider,
             IXIdentityProvider identityProvider,
@@ -50,6 +52,7 @@ namespace xFileService.Providers
         {
             //
             Hub = hub;
+            TagProvider = tagProvider;
             FileRepository = fileRepository;
             StorageProvider = storageProvider;
             IdentityProvider = identityProvider;
@@ -155,6 +158,262 @@ namespace xFileService.Providers
             //
             return result;
         }
+
+        /// <summary>
+        /// Check Specified User Info Has Permissions for Specified File ...
+        /// </summary>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        private async Task<bool> HasPermission(
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            var result = false;
+
+            //
+            // Validate ...
+            result = !id.IsNull() &&
+                !id.IsDefaultGuid() &&
+                !userInfo.IsNullOrDefault();
+            if (!result)
+            {
+                XException.InvalidArgs.Throw();
+            }
+
+            //
+            // Check Item Exists ...
+            result = await IsExists(id);
+            if (!result)
+            {
+                XException.NotFound.Throw();
+            }
+
+            //
+            // Retrieve Dto ...
+            var dto = await Get(id);
+            result = !dto.IsNullOrDefault();
+            if (!result)
+            {
+                XException.ActionFailed.Throw();
+            }
+
+            //
+            result =
+                dto.OwnerId == userInfo.UserId ||
+                userInfo.Roles.Any(r => r.ToNormalString() == "admin");
+
+            //
+            return result;
+        }
+        #endregion
+
+        //
+        #region Tags ...
+        /// <summary>
+        /// Attach Tag to Specified File ...
+        /// </summary>
+        /// <param name="tag"></param>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        public async Task TagAttach(
+            string tag,
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid = !tag.IsNullOrEmpty() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid() &&
+                !userInfo.IsNullOrDefault();
+            if (isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                try
+                {
+                    await TagProvider.Attach(tag, id);
+                }
+                catch { }
+            }
+        }
+
+        /// <summary>
+        /// Detach Tag fro Specified File ...
+        /// </summary>
+        /// <param name="tag"></param>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        public async Task TagDetach(
+            string tag,
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid = !tag.IsNullOrEmpty() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid();
+            if (isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                try
+                {
+                    await TagProvider.Detach(tag, id);
+                }
+                catch { }
+            }
+        }
+
+        /// <summary>
+        /// Attach Tags for Specified File ...
+        /// </summary>
+        /// <param name="tags"></param>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        public async Task TagsAttach(
+            IEnumerable<string> tags,
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid = !tags.IsNull() &&
+                tags.HasChild() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid();
+            if (isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                try
+                {
+                    //
+                    foreach (var tag in tags)
+                    {
+                        await TagAttach(tag, id);
+                    }
+                }
+                catch { }
+            }
+        }
+
+        /// <summary>
+        /// Detach Tags for Specified File ...
+        /// </summary>
+        /// <param name="tags"></param>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        public async Task TagsDetach(
+            IEnumerable<string> tags,
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid = !tags.IsNull() &&
+                tags.HasChild() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid();
+            if (isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                try
+                {
+                    //
+                    foreach (var tag in tags)
+                    {
+                        await TagDetach(tag, id);
+                    }
+                }
+                catch { }
+            }
+        }
+
+        /// <summary>
+        /// Detach all Attached Tags for Specified File ...
+        /// </summary>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        public async Task TagsDetach(
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid = !id.IsNull() && !id.IsDefaultGuid();
+            if (isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                try
+                {
+                    //
+                    var tags = await TagProvider.RemoveTagsFor(id);
+                }
+                catch { }
+            }
+        }
         #endregion
 
         //
@@ -478,6 +737,17 @@ namespace xFileService.Providers
                 result.Add(model.Id);
             }
 
+            //
+            // Remove Tags ...
+            if (!result.IsNull() && result.HasChild())
+            {
+                //
+                foreach (var id in result)
+                {
+                    await TagsDetach(id);
+                }
+            }
+
             //
             return result;
         }
@@ -642,6 +912,206 @@ namespace xFileService.Providers
         }
         #endregion
 
+        //
+        #region Reference ...
+        /// <summary>
+        /// Get Reference Identifier for Specified Provider and Specified File ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <param name="id"></param>
+        /// <returns></returns>
+        public string GetIdentifier(
+            string providedFor,
+            Guid id
+        )
+        {
+            return $"{providedFor}_{id}";
+        }
+
+        /// <summary>
+        /// Check Specified File has Refernce to Provider ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <returns></returns>
+        public async Task<bool> IsProvidedFor(
+            string providedFor,
+            Guid id
+        )
+        {
+            //
+            // Validate ...
+            var isValid =
+                !providedFor.IsNullOrEmpty() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid();
+            if (!isValid)
+            {
+                XException.InvalidArgs.Throw();
+            }
+
+            //
+            // Check Exists ...
+            isValid = await IsExists(id);
+            if (!isValid)
+            {
+                XException.NotFound.Throw();
+            }
+
+            //
+            var dto = await Get(id);
+            isValid = !dto.IsNullOrDefault();
+            if (!isValid)
+            {
+                XException.ActionFailed.Throw();
+            }
+
+            //
+            var identifier = GetIdentifier(providedFor, id);
+            var result =
+                dto.References.IsNull() &&
+                dto.References.HasChild() &&
+                dto.References.Any(r => r.ToNormalString() == identifier.ToNormalString());
+
+            //
+            return result;
+        }
+
+        /// <summary>
+        /// Add Specified Reference to Specified File ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        public async Task AddReference(
+            string providedFor,
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid =
+                !providedFor.IsNullOrEmpty() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid() &&
+                !userInfo.IsNullOrDefault();
+            if (!isValid)
+            {
+                XException.InvalidArgs.Throw();
+            }
+
+            //
+            // Check Has Reference or not ...
+            isValid = await IsProvidedFor(providedFor, id);
+            if (!isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                var dto = await Get(id);
+                isValid = !dto.IsNullOrDefault();
+                if (!isValid)
+                {
+                    XException.ActionFailed.Throw();
+                }
+
+                //
+                var identifier = GetIdentifier(providedFor, id);
+                dto.References.Add(identifier);
+
+                //
+                dto = await Update(
+                    id: dto.Id,
+                    item: dto,
+                    userInfo: userInfo
+                );
+                isValid = !dto.IsNullOrDefault();
+                if (!isValid)
+                {
+                    XException.ActionFailed.Throw();
+                }
+            }
+        }
+
+        /// <summary>
+        /// Remove Specified Reference from Specified File ...
+        /// </summary>
+        /// <param name="providedFor"></param>
+        /// <param name="id"></param>
+        /// <param name="userInfo"></param>
+        /// <returns></returns>
+        public async Task RemoveReference(
+            string providedFor,
+            Guid id,
+            XUserClaimsInfoDto userInfo = null
+        )
+        {
+            //
+            // Validate ...
+            var isValid =
+                !providedFor.IsNullOrEmpty() &&
+                !id.IsNull() &&
+                !id.IsDefaultGuid() &&
+                !userInfo.IsNullOrDefault();
+            if (!isValid)
+            {
+                XException.InvalidArgs.Throw();
+            }
+
+            //
+            // Check Has Reference or not ...
+            isValid = await IsProvidedFor(providedFor, id);
+            if (isValid)
+            {
+                //
+                // Check Permissions ...
+                isValid = await HasPermission(
+                    id: id,
+                    userInfo: userInfo
+                );
+                if (!isValid)
+                {
+                    XException.NotAllowed.Throw();
+                }
+
+                //
+                // Retrieve Dto ...
+                var dto = await Get(id);
+                isValid = !dto.IsNullOrDefault();
+                if (!isValid)
+                {
+                    XException.ActionFailed.Throw();
+                }
+
+                //
+                var identifier = GetIdentifier(providedFor, id);
+                dto.References = dto.References
+                    .Where(r => r.ToNormalString() != identifier.ToNormalString())
+                    .ToList();
+                dto = await Update(
+                    id: dto.Id,
+                    item: dto,
+                    userInfo: userInfo
+                );
+                isValid = !dto.IsNullOrDefault();
+                if (!isValid)
+                {
+                    XException.ActionFailed.Throw();
+                }
+            }
+        }
+        #endregion
+
         //
         #region Data Model ...
         /// <summary>
@@ -831,6 +1301,18 @@ namespace xFileService.Providers
             }
 
             //
+            // Check Permissions ...
+            isValid = await HasPermission(
+                id: id,
+                userInfo: userInfo
+            );
+            if (!isValid)
+            {
+                XException.NotAllowed.Throw();
+            }
+
+            //
+            // Retrieve Entity ...
             var entity = await FileRepository.GetAsync(id);
             if (entity.IsNullOrDefault())
             {
@@ -845,9 +1327,11 @@ namespace xFileService.Providers
                 {
                     nameof(XFile.Id),
                     nameof(XFile.Deleted),
-                    nameof(XFileDto.Owner)
+                    nameof(XFileDto.Owner),
+                    nameof(XFile.References),
                 }
             );
+            entity.References = item.References.ToListString();
             if (entity.IsNullOrDefault())
             {
                 XException.InvalidData.Throw();
@@ -861,16 +1345,7 @@ namespace xFileService.Providers
             }
 
             //
-            // Validate Action ...
-            isValid =
-                entity.OwnerId == userInfo.UserId ||
-                userInfo.Roles.Any(r => r.ToNormalString() == "admin".ToNormalString());
-            if (!isValid)
-            {
-                XException.NotAllowed.Throw();
-            }
-
-            //
+            // Converts to Dto ...
             var result = await ToDto(entity);
 
             //
@@ -915,10 +1390,11 @@ namespace xFileService.Providers
             }
 
             //
-            // Validate Action ...
-            isValid =
-                result.OwnerId == userInfo.UserId ||
-                userInfo.Roles.Any(r => r.ToNormalString() == "admin".ToNormalString());
+            // Check Permissions ...
+            isValid = await HasPermission(
+                id: id,
+                userInfo: userInfo
+            );
             if (!isValid)
             {
                 XException.NotAllowed.Throw();
@@ -938,6 +1414,10 @@ namespace xFileService.Providers
                 XException.ActionFailed.Throw();
             }
 
+            //
+            // Removing Tags ...
+            await TagProvider.RemoveTagsFor(result.Id);
+
             //
             return result;
         }