Wat is difference in (Web Application & Web services)

I am (very)new to Asp.net. Though i am web-developer using Classic ASP/MS-access.

[COLOR=sienna]I want to know what is basic difference between “ASP.net Web Application” and "ASP.net Web Service[/COLOR]"

B4 Starting Asp.net i know one thing that it is not a newer version of Classic ASP, It’s entirely advanced concept.

Anyway i feel that .net Web Application relates to Complete website developed in .net. If i am right then What is Web Service?? How it differs.