Greeklish, a portmanteau of the words Greek and English, also known as Grenglish, Latinoellinika/Λατινοελληνικά or ASCII Greek, is the Greek language written using the Latin alphabet. Unlike standardized systems of Romanization of Greek, as used internationally for purposes such as rendering Greek proper names or place names, or for bibliographic purposes, the term Greeklish mainly refers to informal, ad-hoc practices of writing Greek text in environments where the use of the Greek alphabet is technically impossible or cumbersome, especially in electronic media. Greeklish was commonly used on the Internet when Greek people communicate by forum, e-mail, IRC, instant messaging and occasionally on SMS, mainly because older operating systems didn't have the ability to write in Greek, or in a unicode form like UTF-8. Nowadays most Greek language content appears in native Greek alphabet.
Sometimes, the term Greeklish is also used informally for a non-standard language variety used by bilingual speakers of English and Greek, i.e. Greek with heavy admixture of English words or vice versa.
Read more about Greeklish: History, Orthographic and Phonetic Greeklish, Books Written in Greeklish, Computer Usage of Greeklish, Current Trends, Greeklish-to-Greek Conversion