Welsh, called Cymraeg or Cymric (from Cymru, "Wales") by its speakers, is the native language of Wales and the most flourishing of the Celtic languages. It is spoken in Wales (where the majority of its users also speak English) and in some communities in the United States and Argentina. Organizations such as the Society for the Welsh Language have saved the language from dying out and are working to assure its official status along with English. Several schools in Wales now use Welsh as the medium of instruction, and television and radio broadcasts are made in the language. On the Web you can find a lot of resources on it, too.

Like Breton, Welsh has discarded case endings for nouns; verbs, however, are elaborately inflected. The alternation of consonants, called mutation, plays a role, as in all Celtic languages. Welsh spelling is phonemic, representing unambiguously the pertinent sounds. In most cases Welsh speakers will know how to pronounce a word they have never seen before. The letter w can represent either a consonant or a vowel, however, and y stands for two vowel sounds. The consonant f has the sound of English [v]; ff of [f]. Popular attempts to describe pronunciation of double l (ll) all fail - there is no such sound in the International Phonetic Alphabet. It is a voiceless lateral fricative, and facile comparison to English thl is invalid. Welsh words are accented on the next to last syllable and have a characteristic intonation.

Scholars recognize three periods of Welsh: Old (800-1100), Middle (1100-1500), and Modern (from 1500). Old Welsh survives only in isolated words and names, plus a few lines of verse. Welsh has borrowed words throughout all these periods from Latin, Anglo-Saxon, Norman French, and extensively from English, but it still has a large native vocabulary of Celtic origin. Forty dialects have been identified in Wales. Standard Welsh has both a Northern and Southern variety.