Do you know if java free?

I want to know if Java is free? Can I develop my own application, and running on a Java support computer for free without any license fee? If I develope a website with Java technology, do you know if there is any service application for free, is Tomcat free? Does SUN released this kind software for free? If it does what's its name. If it doesn't do you know any others? At last, do you know any that using JAVA will charge fees.