A network is when two or more electronic devices are linked together to share information.
Did you know that the Internet is considered a network?
What is a LAN and a WAN?
A LAN is a Local Are Network like what you have at home. Devices can be connected to a LAN through an Ethernet cable or connected wirelessly. Wireless connections are made possible by WAPs, Wireless Access Points. Apple's Airport Extreme is a WAP.
A WAN is a Wide Area Network and enables your system to have a faster and more global network. A WAN is what you have across your School District.
Within your network you have Firewalls. These are set up to protect your network from receiving or sending information through your network. The administrator in charge of your Firewalls is the one setting up these blocks. For instance, my school district uses Firewalls to block sites they do not want students accessing. The Firewalls protect our devices and help to reduce help tickets within IT.
In your home, as well as having a WAP, you also have a router. The router allows you to connect multiple devices to your network. Often times, your Internet provider will supply you with a router of their choosing. Your router also connects with your wireless TV or printer.