Hi Leah,
Welcome to JavaRanch!
Every Java class (servlets or otherwise) can have one or more
constructors, which are essentially special methods whose name is the same as the class, and which have no return type; one of these methods will be called automatically when an instance of the class is created using "new". Constructors can have arguments, just like normal functions, and these arguments can be used in the initialization of the class.
Servlets are created in a funny way by a servlet container, and this funny way means that arguments can't be passed as constructor arguments; so instead, servlets have an init() method which is really just a substitute for a constructor. The java.applet.Applet class -- an
applet is to a Web browser what a Servlet is to a Web server -- also has an init() method, for a similar reason.