SOAP
SOAP (Simple Object Access Protocol) is a protocol for exchanging structured information in web services using XML. It defines a messaging framework for communication between applications over networks, typically using HTTP or SMTP as transport. SOAP APIs are known for their strict standards, built-in error handling, and support for complex operations, making them common in enterprise and legacy systems.
Developers should learn SOAP for maintaining or integrating with legacy enterprise systems, financial services, or government applications where standardized, secure, and reliable communication is required. It's particularly useful in scenarios involving complex transactions, such as in banking or healthcare, due to its built-in WS-Security standards and support for stateful operations.