Plugin Types in TeamCity
TeamCity mainly consists of two parts:
The server that gathers information while builds are running
Agents that run builds and send information to server
Consequently, depending on where the code runs, there are
server-side plugins
agent-side plugins.
Aside from that, plugins are divided into the following types :
Build runners
VCS plugins
Notifiers
User authentication plugins
Build Triggers
Extensions, which can modify some aspects of TeamCity behavior. There are several extension points on the server and on the agent, for example, it is possible to format stack trace on the web the way you need or modify build status text, Extensions.
Plugins can also modify TeamCity web UI. They can provide custom content to the existing pages (again, there are several extension points provided for that), or create new pages with their own UI, Web UI Extensions.