Spyware is:

... any program or software tool which tries to collest information about a computer, person or organization without their knowledge, and can send this information back to an unauthorized third party. Spyware can be involved in the identity theft process. Spyware can be detected and removed by various anti spyware tools. Read more about spyware ...

Adware is:

... a software that displays pop-up advertisements on your computer screen whenever the software is running. Adware may be a stand-alone software product, or can be bundled with freeware or shareware. Adware may also install unwanted components onto your computer that may track personal information. Adware can be detected and removed by various anti adware tools. Read more about adware ...

How to protect against spyware and adware:

Protection against malicious software is one of the most important jobs in the computer world. There are few basic rules to prevent badware and spyware. Read more about protection against spyware and adware ...