Galician and Portuguese are the two branches of a dead common language which was spoken in Lusitania and Galicia until it was to break in two in the 15th century. The texts in this father-tongue have been known since the 12th century and interestingly, they do not differ whether from Portugal or Galicia. But later on, because Galicia was ruled by Spanish kings, the languages became separate. In official spheres in Galicia, Spanish (Castillian) spread very fast, helped along by the fact of Galician's being restricted to use in private life. It might have become extinct, but the revival started in the 19th century has by now caused it to flourish once again. The linguistic borders between Galician, Spanish and Portuguese are very flexible, and some local dialects can seem distant from the literary tongue.
Nowadays in fact more than 4 million people speak Galician as a first language, and it stands as one of the official tongues of the Galician autonomous region. In phonetics Galician resembles Spanish very much: no phoneme [z], nasal vowels present, there are sounds like English [sh] and its voiceless [th], the "thorn". Sounds for b and v are the same.
But the grammatical structure differs from Spanish and still has much in common with Portuguese. Its significant feature is Galician's absence of analytic verb forms.