Difference between lan and wan.

What is the difference between lan and wan.

The fundamental concept behind LAN and WAN is same. Both are the types of computer networks. The difference becomes clear if you expand the abbreviations.
The term LAN stands for Local Area Network which is a type of network that is used to connect systems across a specific area, usually within a building or campus etc whereas the term WAN stands for Wide Area Network which unlike the LAN, can provide a computer network across geographical boundaries, across countries. Example of WAN is Internet.
So, in short, the main difference between a LAN and WAN is the area that they can cover.