Say you are searching for something on google, lets say a video, for example
search google for, Aladdin full movie, now like me, it pisses you off when ya click the video tab and get all youtube videos, only to click on them to be given some bullshit video that tells you to register at some sketchy website in order to watch it.
What you can do is type in this line after your search
-site:sitename.com (example) -site:youtube.com
So now search google for,
Aladdin full movie -site:youtube.com
This will filter out all those annoying youtube spam videos