Mining algorithm is refer to the algorithm of blackchain. When you mine a coin, you need to use the right algorithm to mine. There are many many algorithms on the market right now. Some algorithms are only mining with CPU, some are for both CPU and GPU., some are for CPU, GPU and ASIC. However, if there is ASIC exist on that algorithm, CPU and GPU mining is pretty much useless on that algorithm.
I will go over some popular GPU algorithms and ASIC algorithms since those where is the real mining money in.
GPU Algorithm (CPU can mine but not so recommended)
Popular coin Ethereum ETH is one of big name using this algorithm. DAG epoch file size will increase time by time. If the DAG size is bigger than your GPU memory size. Your GPU will become useless on that coin.
The coin list use Etash
Ethereum Classic (ETC)
Popular coin Menoro XMR is one of big name using this algorithm. It is also CPU minable alog.
The coin list use Cryptonight
Popular coin Zcash is one of big name using this algorithm. Some Nvidia GPU has better performance on this algorithm.
The coin list use Equihash
ASIC Algorithm (CPU & GPU can also mine but do NOT waste your time)
Popular coin Bitcoin is one them using this algorithm.
The coin list use SHA-256
Deutsche eMark (DEM)
Popular coin Litecoin is one them using this algorithm.
The coin list use scrypt
Popular coin Dash is one them using this algorithm.
The coin list use X11