WSGI is "Web Server Gateway Interface"

The WSGI docs says:

It is a specification for web servers and application servers to communicate with web applications (though it can also be used for more than that). It is a Python standard, described in detail in PEP 333.

WSGI is useful to TiddlyWeb for three reasons:

• It makes it easy to create web applications and services independent of the web server through which the services will run. This means it is easy to run simple servers for development and debugging as well as very powerful servers for high load situations.
• It makes it easy to layer web applications to add functionality that is decoupled.
• WSGI encourages the development of highly transparent services.

A WSGI application is identified by the signature of a function or class and the contract of its return value. A WSGI application is a {{{callable}}} that takes environ and start_response as arguments and returns an iterator.