Jetty is decomposed into many jars providing utilities, HTTP, server, client, servlets and many optional features. It can be difficult to track which jars are required and their dependencies.
The Jetty Dependencies reference explains the jetty jar structure.
The individual jetty jars may be used directly by constructing your own classpath, or the start.jar utility can be used to build a classpath.
During development, the maven build tool is ideal for accessing jetty jars and their dependencies.
The aggregate jars may also used to reduce the number of jars required.