System.AppContext by: Microsoft

Provides the System.AppContext class, which allows access to the BaseDirectory property and other application specific data. Commonly Used Types: System.AppContext

System.Collections by: Microsoft

Provides classes that define generic collections, which allow developers to create strongly typed collections that provide better type safety and performance than non-generic strongly typed collections. Commonly Used Types: System.Collections.Generic.List<T> System.Collections.Generic.Dictionary<TKey, TValue> System.Collections.Generic.Queue<T> System.Collections.Generic.Stack<T> System.Collections.Generic.HashSet<T> System.Collections.Generic.LinkedList<T> System.Collections.Generic.EqualityComparer<T> System.Collections.Generic.Comparer<T> System.Collections.Generic.SortedDictionary<TKey, TValue>

System.Collections.Concurrent by: Microsoft

Provides several thread-safe collection classes that should be used in place of the corresponding types in the System.Collections.NonGeneric and System.Collections packages whenever multiple threads are accessing the collection concurrently. Commonly Used Types: System.Collections.Concurrent.ConcurrentDictionary<TKey, TValue> System.Collections.Concurrent.ConcurrentQueue<T> System.Collections.Concurrent.ConcurrentBag<T> System.Collections.Concurrent.BlockingCollection<T> System.Collections.Concurrent.ConcurrentStack<T>

System.Collections.NonGeneric by: Microsoft

Provides classes that define older non-generic collections of objects, such as lists, queues, hash tables and dictionaries. Developers should prefer the generic collections in the System.Collections package. Commonly Used Types: System.Collections.ArrayList System.Collections.Hashtable System.Collections.CollectionBase System.Collections.ReadOnlyCollectionBase System.Collections.Stack System.Collections.SortedList System.Collections.DictionaryBase System.Collections.Queue System.Collections.Comparer System.Collections.CaseInsensitiveComparer

System.Collections.Specialized by: Microsoft

Provides older specialized non-generic collections; for example, a linked list dictionary, a bit vector, and collections that contain only strings. Commonly Used Types: System.Collections.Specialized.NameValueCollection System.Collections.Specialized.NameObjectCollectionBase System.Collections.Specialized.StringCollection System.Collections.Specialized.IOrderedDictionary System.Collections.Specialized.HybridDictionary System.Collections.Specialized.OrderedDictionary System.Collections.Specialized.ListDictionary System.Collections.Specialized.StringDictionary System.Collections.Specialized.BitVector32

System.ComponentModel by: Microsoft

Provides interfaces for the editing and change tracking of objects used as data sources. Commonly Used Types: System.ComponentModel.CancelEventArgs System.IServiceProvider System.ComponentModel.IEditableObject System.ComponentModel.IChangeTracking System.ComponentModel.IRevertibleChangeTracking

System.ComponentModel.Annotations by: Microsoft

Provides attributes that are used to define metadata for objects used as data sources. Commonly Used Types: System.ComponentModel.DataAnnotations.ValidationResult System.ComponentModel.DataAnnotations.IValidatableObject System.ComponentModel.DataAnnotations.ValidationAttribute System.ComponentModel.DataAnnotations.RequiredAttribute System.ComponentModel.DataAnnotations.StringLengthAttribute System.ComponentModel.DataAnnotations.DisplayAttribute System.ComponentModel.DataAnnotations.RegularExpressionAttribute System.ComponentModel.DataAnnotations.DataTypeAttribute System.ComponentModel.DataAnnotations.RangeAttribute System.ComponentModel.DataAnnotations.KeyAttribute

System.ComponentModel.EventBasedAsync by: Microsoft

Provides support classes and delegates for the event-based asynchronous pattern. Developers should prefer the classes in the System.Threading.Tasks package. Commonly Used Types: System.ComponentModel.AsyncCompletedEventArgs System.ComponentModel.AsyncCompletedEventHandler System.ComponentModel.ProgressChangedEventArgs System.ComponentModel.ProgressChangedEventHandler System.ComponentModel.AsyncOperation System.ComponentModel.AsyncOperationManager

System.ComponentModel.Primitives by: Microsoft

Provides interfaces that are used to implement the run-time and design-time behavior of components. Commonly Used Types: System.ComponentModel.IComponent System.ComponentModel.IContainer System.ComponentModel.ISite System.ComponentModel.ComponentCollection

System.ComponentModel.TypeConverter by: Microsoft

Provides the System.ComponentModel.TypeConverter class, which represents a unified way of converting types of values to other types. Commonly Used Types: System.ComponentModel.TypeConverter System.ComponentModel.TypeConverterAttribute System.ComponentModel.PropertyDescriptor System.ComponentModel.StringConverter System.ComponentModel.ITypeDescriptorContext System.ComponentModel.EnumConverter System.ComponentModel.TypeDescriptor System.ComponentModel.Int32Converter System.ComponentModel.BooleanConverter System.ComponentModel.DoubleConverter

System.Composition by: Microsoft

This packages provides a version of the Managed Extensibility Framework (MEF) that is lightweight and specifically optimized for high throughput scenarios, such as the web. Commonly Used Types: System.Composition.ExportAttribute System.Composition.ImportAttribute System.Composition.Convention.ConventionBuilder System.Composition.Hosting.CompositionHost System.Composition.CompositionContext System.Composition.CompositionContextExtensions

System.Console by: Microsoft

Provides the System.Console class, which represents the standard input, output and error streams for console applications. Commonly Used Types: System.Console System.ConsoleColor

System.Data.Common by: Microsoft

Provides the base abstract classes, including System.Data.DbConnection and System.Data.DbCommand, for all data providers. Commonly Used Types: System.DBNull System.Data.Common.DbConnection System.Data.Common.DbException System.Data.Common.DbParameter System.Data.DbType System.Data.Common.DbDataReader System.Data.Common.DbCommand System.Data.Common.DbTransaction System.Data.Common.DbParameterCollection System.Data.Common.DbProviderFactory

System.Data.SqlClient by: Microsoft

Provides the data provider for SQL Server. These classes provide access to versions of SQL Server and encapsulate database-specific protocols, including tabular data stream (TDS) Commonly Used Types: System.Data.SqlClient.SqlConnection System.Data.SqlClient.SqlException System.Data.SqlClient.SqlParameter System.Data.SqlDbType System.Data.SqlClient.SqlDataReader System.Data.SqlClient.SqlCommand System.Data.SqlClient.SqlTransaction System.Data.SqlClient.SqlParameterCollection System.Data.SqlClient.SqlClientFactory

System.Diagnostics.Contracts by: Microsoft

Provides static classes for representing program contracts such as preconditions, postconditions, and invariants. Commonly Used Types: System.Diagnostics.Contracts.Contract System.Diagnostics.Contracts.ContractClassAttribute System.Diagnostics.Contracts.ContractClassForAttribute System.Diagnostics.Contracts.ContractFailureKind System.Runtime.CompilerServices.ContractHelper System.Diagnostics.Contracts.ContractInvariantMethodAttribute System.Diagnostics.Contracts.PureAttribute System.Diagnostics.Contracts.ContractArgumentValidatorAttribute System.Diagnostics.Contracts.ContractVerificationAttribute System.Diagnostics.Contracts.ContractOptionAttribute

System.Diagnostics.Debug by: Microsoft

Provides classes and attributes that allows basic interaction with a debugger. Commonly Used Types: System.Diagnostics.Debug System.Diagnostics.DebuggerStepThroughAttribute System.Diagnostics.Debugger System.Diagnostics.DebuggerDisplayAttribute System.Diagnostics.DebuggerBrowsableAttribute System.Diagnostics.DebuggerBrowsableState System.Diagnostics.DebuggerHiddenAttribute System.Diagnostics.DebuggerNonUserCodeAttribute System.Diagnostics.DebuggerTypeProxyAttribute

System.Diagnostics.DiagnosticSource by: Microsoft

Provides Classes that allow you to decouple code logging rich (unserializable) diagnostics/telemetry (e.g. framework) from code that consumes it (e.g. tools) Commonly Used Types: System.Diagnostics.DiagnosticListener System.Diagnostics.DiagnosticSource

System.Diagnostics.FileVersionInfo by: Microsoft

Provides the System.Diagnostics.FileVersionInfo class, which allows access to Win32 version resource information for a physical file on disk. Commonly Used Types: System.Diagnostics.FileVersionInfo

System.Diagnostics.Process by: Microsoft

Provides the System.Diagnostics.Process class, which allows interaction with local and remote processes. Commonly Used Types: System.Diagnostics.Process System.Diagnostics.ProcessModule System.Diagnostics.ProcessStartInfo System.Diagnostics.ProcessThread

System.Diagnostics.Tools by: Microsoft

Provides attributes, such as GeneratedCodeAttribute and SuppresMessageAttribute, that are emitted or consumed by analysis tools. Commonly Used Types: System.CodeDom.Compiler.GeneratedCodeAttribute System.Diagnostics.CodeAnalysis.SuppressMessageAttribute