Computing uses three number bases:- Binary (base 2), Octal (base 8) and Hexadecimal (base 16). Binary has been described before, although various catchphrases are used to describe their length.
4 bits    e.g. 1100 is termed nibble 
 
8 bits    e.g. 11001111 us termed Byte 
 
16 bits e.g.  1100111111001111   is termed Word 
 
32 bits e.g. 11001111110011111100111111001111    is termed long word. 
 
Hexadecimal (Hex) is a common base; it uses 0 -> 9 and A -> F for 10 -> 15. Conversion to decimal is achieved by using weighted columns of 16n similar to binary. Within microprocessors we often convert from binary to hex and back, a short hand way of doing this is shown below.