TeamCity is a build management and continuous integration tool created by JetBrains that allows building pipelines of steps. It supports over 2000 projects with 12,000 build configurations running on 500 agents. Key features include a Kotlin DSL, HA read-only servers, Docker runner improvements, templates for step ordering, enforced settings, .NET Core support, and plugins. Pipelines allow breaking up builds into sequential steps like compiling, running tests, and publishing results to improve efficiency.