What other lens brands are compatible with Nikon?

I want to get more lenses for my Nikon D3100. However I don't really want to buy Nikon Nikkor lenses. They seem to be more expensive than other brands. So what other brands will work with my Nikon? Could I use a Cannon or Sony lens?

There are some other 3rd party lenses but I don't trust them so I don't buy them any more. I do one one that has focus and aberration issues.

Nikon and Canon (which I use) lenses are more expensive because they're far better quality.
Never buy camera gear based on price - a very bad idea. Trust me, the lower the price the lower the quality of the product, plain and simple.

Sigma, Tokina, tamron, Rokinon, and others. Canon and Sony are not directly compatible. Sometimes there are adapters that can be used, but you lose features.

You can only use lenses that come with a Nikon F-mount. Sigma, Tamron, and Tokina are some third-party lens makers that offer Nikon mount lenses. Don't expect full compatibility though but for most people, they are good enough for the price. Then there are also brands like Promaster that rebrand lenses that have a Nikon mount. Most of the time, these even go cheaper than third-party brands. Just make sure you understand that in photography, you get exactly what you pay for.

You can use an adapter to force another lens mount to work in your camera but most of the time, you will lose automatic functions.

If you want to take pix just for hobby and time pass, don't buy expensive lens.bt if you want to enhance your photography skill level. Then you must buy branded lense.becasue in future you may want to upgrade your basic entry level camera to semi-pro or pro cameras.

Not any of the camera manufacturers such as Canon or Sony or Pentax (anyway in comparable price range to Nikon for similar lenses). Independents such as Sigma, Tamron, Tokina will fit, but you must specify it's for Nikon when you buy. If you buy wrong mount it's just like buying Canon etc - no go.

If you want autofocus your other options are:

Sigma but only the models labeled HSM (and the motorized versions of the 70-300)
Tamron but only the lenses where it says "Nikon with Built-In Motor" on the specs sheet.

That's it.

Sigma, Tokina, Tamron. Just be sure you specify Nikon mount, as they make lenses for all brands.

Sigma lenses marked HSM will autofocus on your D3100.