An Alphabet is a set of letters. The english language uses one alphabet. It contains 26 letters. A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y AND Z. Many western european languages, such as French, German, Italian and Spanish, use alphabets which use all of the same letters as English. Some languages have additional letters which are not used in English.
In other parts of the world, languages can be written in more than one alphabet. Greek uses both the European Latin alphabet as well as the Cyrillic (Greek) alphabet.