Even if Arabizi means nothing to you, you may use it everyday when you work on your laptop or send messages from your cell-phone. Arabizi is one of the expressions for what is also called ‘arabiyyat al-dardasha, i.e. the more or less phonetic Arabic written with Roman characters in order to use various IT applications when an Arabic keyboard is not available and/or easy to employ.
‘Arabizi – or Aralish, or Franco (for franco-arabe in the Maghreb countries) – is not anymore an absolute necessity in order to communicate in Arabic as it was in the early ‘90s with the very beginning of a widespread Internet but it remains useful at times. Above all, it has become a funny way, now adopted by many young Arabs (and marketed by advertising agencies) to express oneself with the too serious and intimidating written Arabic.
It is worth mentioning that the mere existence of Arabizi gives some credit to those who think that something like a “common Arab culture” still exists! Indeed, Arabizi has appeared and developed itself as an accepted code among all IT Arab users, without any interference of any kind from any official body.
Arabisi may be understood as a new lingua franca (the "lingua franca" was a kind of pidgin, mainly a mixture of Arabic and various Roman languages, which was still in use around the Mediterranean shores at the end of the 19th century). Promoted by the more dynamic and globalised segments of the society, Arabizi is the language of the youth, a language which has absolutely no respect for the older elites and for their command of the (difficult) written Arabic used as a tool for their “symbolic domination”.
Indeed, many (grown-up) people will condemn such a “foolish” attitude toward the Arabic language which is considered to be the core symbol of the Arabic and/or Islamic community. And sometimes they could not be blamed when you watch ads like the one which promotes Maren, one of the tools developed to type Arabic from an English keyboard: it gives the impression that nobody had never typed in Arabic before Microsoft software!
Even more, the ones who are afraid of the spread of these news tools which make easier the shift from the Arabic to the Latin alphabet remember that if the use of the Arabic alphabet in order to transcript other languages like Berber, Persian, Urdu and many others has been historically the rule, in modern times, the first example which comes to mind is, on the contrary, the romanisation of the Turkish language in 1928, shortly after another very symbolic decision by Kamal Atatürk, the abolition of the Califate in 1924.
Links to the some softwares for a “romanised” writing of Arabic to be found in the original post in French.