Will Sigma lenses fit onto a Nikon D3000?

I need a new lens but for a cheaper cost then a regular Nikon lens. Any help or suggestions? I'm looking for a zoom lens bigger then 18-55mm and a nice Fstop, under f/5 would be nice.

First, and this applies to all camera gear, the cheaper it is the lesser the quality - a simple fact of this gear. More expensive camera, higher technical quality - same with lenses. Buy cheaper, get cheaper.

Yes, Sigma lenses "for Nikon" can be fitted on your D3000. Check your nearest camera shop.

Yes it will fit as long as you get it with a Nikon mount. Sigma is a third-party lens maker manufacturing lenses for different camera mounts. Make sure you get the lens with the mount your camera has, that's a Nikon F-mount.

The 18-55mm is a very good lens if you know how to use it properly. See this article to know how to look at lenses.

http://keerok-photography.blogspot.com/2011/05/lenses-so-many-of-them-there-is-no-best.html