HttpContext

HttpContext is an object that encapsulates all HTTP-specific information about a single HTTP request and its corresponding response within a web application. It provides access to the request data, the response to be sent, session and user information, and per-request data storage. In many frameworks, HttpContext is created at the start of a request and disposed at the end, allowing middleware, controllers, and services to share information during processing.

In the classic ASP.NET framework, HttpContext is defined in System.Web and includes properties such as Request, Response, Session, User, Items, and Server. HttpContext.Current historically exposed the current context on the executing thread, enabling code in various layers to access per-request data. This model relies on thread affinity and the ASP.NET pipeline.

In ASP.NET Core, HttpContext is part of Microsoft.AspNetCore.Http and is accessed via the HttpContext property on controllers and middleware. It is not stored in a global static field; when needed by non-controller code, developers may inject IHttpContextAccessor. The HttpContext in Core is more modular and can be extended via features, including Request, Response, User, Session (when enabled), and Items, as well as connection info and WebSocket features.

Common usage includes reading request headers, query strings, form data, and cookies; writing response status codes, headers, and cookies; and storing per-request data in the Items collection. HttpContext is central to authentication and authorization decisions through the User principal.

Security and lifecycle notes: avoid relying on static state across requests; ensure proper disposal and consider asynchronous context flow when accessing HttpContext across await/async boundaries.