SOAP stands for Simple Object Access Protocol. It is a messaging protocol specification for exchanging structured information in the implementation of web services in computer networks. SOAP messages are typically formatted using XML (Extensible Markup Language), making them platform-independent and language-neutral. A SOAP message consists of an envelope, a header (optional), and a body. The envelope defines the overall structure of the message, the header contains application-specific information (like routing or security), and the body contains the actual message payload, which is usually an XML document representing a request or a response to a service operation. SOAP is heavily used in enterprise environments for distributed computing, often relying on other transport protocols like HTTP or SMTP. While newer, lighter-weight protocols like REST have gained popularity, SOAP remains relevant, particularly in environments requiring high levels of security, transactional integrity, and formal contracts defined by WSDL (Web Services Description Language). The '.soap' extension is not a standard, universally recognized file extension for storing SOAP messages; these messages are usually transmitted directly over the network or sometimes saved as generic '.xml' files for debugging or archival purposes.