A regular expression is a regular pattern to identify regular language
I still didn't really understand the meaning of 'regular'. What is regular language? why they are regular? and how regular is regular? Because the word 'regular' is too ambiguous to be understood. Is it really mean 'regular'? Is it similar in meaning with 'regular' in 'i'm his regular customer'? or does it refer to something else? I already red the book by Arto Salooma (Jewels of Formal Language Theory). What i can understand is regular expression .. (read the title), and regular language is a language that can be accepted by DFA. But i'm still have something in my instinct that keep saying this is not the complete answer (for sure it is not Salomaa's fault, since he's a REGULAR in formal theory!). So i'm still keep searching to complete my record...
update 12th June 2008
a language is regular if there is an automata or FSA that can accept it - wiki. One can build an automata using transition diagram or transition table.