What is spyware and adware?

Tweet

Can anybody tell what these terms mean? I've a problem on my pc and i think its related to any of these...I signed up for a free three day trial for what i thught was a useful music download site...but after the trial ended, i get about 3-4 reminders daily whenever i connect to the internet, that my trial has ended and i now need to purchase the membership...how can i get rid of this?