For forms, if you want to make it much easier, ALAJAX is there for you. It is a jQuery plugin that automagically converts standard forms into Ajaxed ones, no coding required.
Once inserted and the forms are defined, It blocks the default
POST functionality, analyzes the input types used and sends them as an Ajax request.
Its code is well commented and leaves space for further customizations (extra actions to be taken before/after submitting).
Compatibility: All Major Browsers