A premium domain name is a domain name composed exclusively of letters: A,B,C,D,E,F,G,H,I,L,M,N,O,P,R,S,T. These letters are referred to as “premium letters”.

A premium LLLL.com is, in other words, an LLLL.com devoid of the letters: J,K,Q,U,V,W,X,Y,Z. These letters are commonly referred to as non-premium letters. The letters J,K,U,V,W,Y are considered by most domain investors to be of higher quality than the letters Q,X,Z.

The letters: J,K,U,V,W,Y are commonly referred to as “semi-premium” letters, whereas Q,X,Z are referred to as “bad letters”.