Phoenician was a language originally spoken in the coastal region of what is now Lebanon. Phoenician was a Semitic language of the Canaanite subgroup, closely related to Hebrew. It is known only from inscriptions - such as Ahiram's coffin, Kilamuwa's tomb, Yehawmilk's at Byblos, etc. - and occasional glosses in books in other languages; Roman authors such as Sallust allude to books in Punic, but none have survived (except occasionally in translation; eg Mago's treatise.) The significantly divergent later form of the language that was spoken in the Phoenician colony Carthage is known as Punic; it remained in use for considerably longer than Phoenician did in Phoenicia itself, surviving certainly into Augustine's time and possibly as late as the Arab conquest, if an ambiguous comment of the geographer al-Bakri about people speaking a language neither Berber nor Latin nor Coptic in a city in northern Libya (where Punic survived even past the disappearance of the Phoenician alphabet  (http://www.let.leidenuniv.nl/vtw/jongeling/latpun/LPINTRO.htm)) refers to it.
The differences between Phoenician and Hebrew include certain sound changes: Proto-Semitic â (Hebrew ô) became û, while stressed Proto-Semitic a (Hebrew å) became o, as shown by Latin and Greek transcriptions like rus for "head, cape" (Hebrew rôš); furthermore, the three sibilants (sin, shin, samekh) seem to have merged at a fairly early stage, although the earlier inscriptions do still distinguish them. In later Punic dialect, the gutturals seem to have been entirely lost, and p to have become f throughout (rather than just after vowels, as in Hebrew.) Other differences include grammatical ones - eg the causative (Hebrew hiph‘îl) in yi- or ’î- (orthographically yp‘l, ’yp‘l) and the apparent survivals of case endings in early Phoenician - and vocabulary, for instance the use of kn (as in Arabic) rather than hyh for "be" and p‘l rather than ‘sh for "do", and exclusively bal rather than lô’ for "not".
The earliest known inscriptions in Phoenician come from Byblos and date back to ca. 1000 BC. Phoenician and Punic inscriptions are found in Lebanon, Syria, Israel, Cyprus, Sardinia, Sicily, Tunisia, Morocco, Algeria, and other locations as late as the early centuries of the Christian Era.
Knowledge of Hebrew aided the reconstruction of Phoenician inscriptions. One of the earliest essays in Phoenician language studies was Wilhelm Gesenius (1786 - 1842), Scripturae linguaeque phoeniciae monumenta, 1837, analyzing texts from coins and monumental inscriptions. Nowadays one can study Phoenician in the U.S. at Harvard University, Johns Hopkins University, the University of Michigan and University of Chicago (the only place to study advanced Phoenician).
- Ethnologue report--does not contain much information (http://www.ethnologue.com/show_iso639.asp?code=phn)