Pop ups are ads that can cause your computer to get viruses which causes your computer to slow down, restart, or sometimes freeze. Pop ups show advertisement from companies and some are dangerous such as the ones that say you have won a $100 gift card for lets say Walmart and you have to put in your address to "claim your reward" but its a potential risk to you because someone could be using your address for things. Some advertisements are viruses that trick you into clicking them and then now you have a virus to deal with. Pop-up ads or pop-ups are often forms of online advertising on the World Wide Web intended to attract web traffic or capture email addresses. Pop-ups are generally new web browser windows to display advertisements. I could go on lol....