How do signal interfere with each other?

I was wondering if 2.4GHz signals interfere with each other to lower success rate of transmissions.

I have a wireless router and Im using the uMIRF (nRF2401).

Do these interfere with each other in any way? make noise for each?

Yes, they do. 802.11b/g and bluetooth and the nRF 2.4 GHz signals can interfere. (Also most microwave ovens are in this same 2.4GHz band and can interfere)

802.11a is on a different frequency (~ 5 GHz).