CDMA means Code Division Multiple Access. It's a type of cellphone signal like 3G for example, there's also now 4G, and GSM. Currently 4G is the fastest signal format. The G simply stands for Generation. GSM stands for Global System for Mobile. Furthermore, you know how some cellphones you can get with different providers? Well if you have (for example) a Boost Mobile phone, they only offer GSM and CDMA, where as Verizon for example no longer offers either of these, so if you bought a GSM or CDMA phone, you could get Boost Mobile service for it, but not Verizon.