diff --git a/Sources/ExternalDocumentation.swift b/Sources/ExternalDocumentation.swift
index 841375e..885e21a 100644
--- a/Sources/ExternalDocumentation.swift
+++ b/Sources/ExternalDocumentation.swift
@@ -1,9 +1,30 @@
-//
-//  ExternalDocumentation.swift
-//  SwaggerParser
-//
-//  Created by Logan Shire on 7/12/17.
-//
-//
-
 import Foundation
+import ObjectMapper
+
+/// Allows referencing an external resource for extended documentation.
+public struct ExternalDocumentation {
+
+    /// The URL for the target documentation.
+    let url: URL
+
+    /// A short description of the target documentation. 
+    /// GFM syntax can be used for rich text representation.
+    let description: String?
+}
+
+struct ExternalDocumentationBuilder: Builder {
+
+    typealias Building = ExternalDocumentation
+
+    let url: URL
+    let description: String?
+
+    init(map: Map) throws {
+        url = try map.value("url", using: URLTransform())
+        description = try? map.value("description")
+    }
+
+    func build(_ swagger: SwaggerBuilder) throws -> ExternalDocumentation {
+        return ExternalDocumentation(url: self.url, description: self.description)
+    }
+}
diff --git a/Sources/Operation.swift b/Sources/Operation.swift
index 0dd3589..064b543 100644
--- a/Sources/Operation.swift
+++ b/Sources/Operation.swift
@@ -2,6 +2,10 @@ import ObjectMapper
 
 public struct Operation {
 
+    /// A list of tags for API documentation control. 
+    /// Tags can be used for logical grouping of operations by resources or any other qualifier.
+    public let tags: [String]
+
     /// A short summary of what the operation does. This field SHOULD be less than 120 characters.
     public let summary: String?
 
@@ -32,9 +36,6 @@ public struct Operation {
     /// A unique string used to identify the operation
     public let identifier: String?
 
-    /// A list of tags used to group operations together
-    public let tags: [String]
-
     /// A list of which security schemes are applied to this operation.
     /// The list of values describes alternative security schemes that can be used 
     /// (that is, there is a logical OR between the security requirements).
@@ -59,12 +60,12 @@ struct OperationBuilder: Builder {
     let security: [SecurityRequirement]?
 
     init(map: Map) throws {
+        tags = (try? map.value("tags")) ?? []
         summary = try? map.value("summary")
         description = try? map.value("description")
         externalDocumentationBuilder = try? map.value("externalDocs")
         parameters = (try? map.value("parameters")) ?? []
         identifier = try? map.value("operationId")
-        tags = (try? map.value("tags")) ?? []
 
         let allResponses: [String : Reference<ResponseBuilder>] = try map.value("responses")
         var mappedResponses = [Int : Reference<ResponseBuilder>]()
@@ -91,6 +92,7 @@ struct OperationBuilder: Builder {
             .map { try ResponseBuilder.resolve(swagger, reference: $0) }
 
         return Operation(
+            tags: self.tags,
             summary: self.summary,
             description: self.description,
             externalDocumentation: externalDocumentation,
@@ -99,7 +101,6 @@ struct OperationBuilder: Builder {
             defaultResponse: defaultResponse,
             deprecated: self.deprecated,
             identifier: self.identifier,
-            tags: self.tags,
             security: self.security)
     }
 }
diff --git a/Sources/Swagger.swift b/Sources/Swagger.swift
index 9af9379..e0ceebd 100644
--- a/Sources/Swagger.swift
+++ b/Sources/Swagger.swift
@@ -59,6 +59,13 @@ public struct Swagger {
     /// Individual operations can override this definition.
     public let security: [SecurityRequirement]
 
+    /// A list of tags used by the specification with additional metadata. 
+    /// The order of the tags can be used to reflect on their order by the parsing tools. 
+    /// Not all tags that are used by the Operation must be declared.
+    /// The tags that are not declared may be organized randomly or based on the tools' logic. 
+    /// Each tag name in the list MUST be unique.
+    public let tags: [Tag]
+
     /// Additional external documentation.
     public let externalDocumentation: ExternalDocumentation?
 }
@@ -93,6 +100,7 @@ struct SwaggerBuilder: Builder {
     let responses: [String : ResponseBuilder]
     let securityDefinitions: [String : SecuritySchemaBuilder]
     let security: [SecurityRequirement]
+    let tagBuilders: [TagBuilder]
     let externalDocumentationBuilder: ExternalDocumentationBuilder?
 
     init(map: Map) throws {
@@ -128,6 +136,7 @@ struct SwaggerBuilder: Builder {
         responses = (try? map.value("responses")) ?? [:]
         securityDefinitions = (try? map.value("securityDefinitions")) ?? [:]
         security = (try? map.value("security")) ?? []
+        tagBuilders = (try? map.value("tags")) ?? []
         externalDocumentationBuilder = try? map.value("externalDocs")
     }
 
@@ -153,12 +162,14 @@ struct SwaggerBuilder: Builder {
         ParameterBuilder.resolver.teardown()
         ResponseBuilder.resolver.teardown()
 
+        let tags = try self.tagBuilders.map { try $0.build(swagger) }
+        let externalDocumentation = try self.externalDocumentationBuilder?.build(swagger)
         return Swagger(version: self.version, information: try self.information.build(swagger),
                        host: self.host, basePath: self.basePath, schemes: self.schemes,
                        consumes: self.consumes, produces: self.produces, paths: paths,
                        definitions: definitions, parameters: parameters, responses: responses,
                        securityDefinitions: securityDefinitions, security: self.security,
-                       externalDocumentation: try self.externalDocumentationBuilder?.build(swagger))
+                       tags: tags, externalDocumentation: externalDocumentation)
     }
 }
 
diff --git a/Sources/Tag.swift b/Sources/Tag.swift
new file mode 100644
index 0000000..ced0b41
--- /dev/null
+++ b/Sources/Tag.swift
@@ -0,0 +1,36 @@
+import ObjectMapper
+
+/// Allows adding meta data to a single tag that is used by the Operation.
+/// It is not mandatory to have a Tag per tag used there.
+public struct Tag {
+
+    /// The name of the tag.
+    let name: String
+
+    /// A short description for the tag. 
+    /// GFM syntax can be used for rich text representation.
+    let description: String?
+
+    /// Additional external documentation for this tag.
+    let externalDocumentation: ExternalDocumentation?
+}
+
+struct TagBuilder: Builder {
+
+    typealias Building = Tag
+
+    let name: String
+    let description: String?
+    let externalDocumentationBuilder: ExternalDocumentationBuilder?
+
+    init(map: Map) throws {
+        name = try map.value("name")
+        description = try? map.value("description")
+        externalDocumentationBuilder = try? map.value("externalDocs")
+    }
+
+    func build(_ swagger: SwaggerBuilder) throws -> Tag {
+        return Tag(name: self.name, description: self.description,
+                   externalDocumentation: try self.externalDocumentationBuilder?.build(swagger))
+    }
+}