During the last two days, more than 100 websites have popped up using the words "Boston Marathon."
The Massachusetts attorney general says some of them ask you to donate not to help bombing victims--but to make cyber crooks rich.
Other messages are being sent to your inbox. They entice you to watch video of the two explosions. But experts say don't do it. They not only show you video, but also try to infect your computer with a virus.
Remember be careful about your surfing. Get news from legitimate news sources and check out charities before you donate.
We've listed a few places you can turn to that look at the tax filings of nonprofits. That way you know where your dollars are going.