Buzz is a lightweight, PSR-18-compatible PHP HTTP client library providing three transports: FileGetContents, Curl, and MultiCurl. The MultiCurl client supports both asynchronous requests and HTTP/2 server push. Architecture follows a middleware chain pattern through the `Browser` class, which wraps any client and allows request/response modification via pluggable middleware. Built-in middleware covers authentication (Basic, Bearer, Digest, WSSE), cookie management, content-length, content-type auto-detection, request logging, and history recording. The library integrates with Symfony OptionsResolver for configuration validation and supports PSR-7, PSR-17, and php-http/httplug interfaces. It is a mature, stable library primarily in maintenance mode but still receiving compatibility updates and bug fixes.