Insular Celtic languages in the context of "Common Brittonic"

Proto-Celtic, or Common Celtic, is the reconstructed ancestral proto-language of all known Celtic languages, and a descendant of Proto-Indo-European. It is not attested in writing but has been partly reconstructed through the comparative method. Proto-Celtic is generally thought to have been spoken between 1300 and 800 BC, after which it began to split into different languages. Proto-Celtic is often associated with the Urnfield culture and particularly with the Hallstatt culture. Celtic languages share common features with Italic languages that are not found in other branches of Indo-European, suggesting the possibility of an earlier Italo-Celtic linguistic unity.

Proto-Celtic is currently being reconstructed through the comparative method by relying on later Celtic languages. Though Continental Celtic presents much substantiation for Proto-Celtic phonology, and some for its morphology, recorded material is too scanty to allow a secure reconstruction of syntax, though some complete sentences are recorded in the Continental Gaulish and Celtiberian. So, the main sources for reconstruction come from Insular Celtic languages with the oldest literature found in Old Irish and Middle Welsh, dating back to authors flourishing in the 6th century AD.

The morphology of the Welsh language shows many characteristics perhaps unfamiliar to speakers of English or continental European languages like French or German, but has much in common with the other modern Insular Celtic languages: Irish, Scottish Gaelic, Manx, Cornish, and Breton. Welsh is a moderately inflected language. Verbs conjugate for person, tense and mood with affirmative, interrogative and negative conjugations of some verbs. A majority of prepositions inflect for person and number. There are few case inflections in Literary Welsh, being confined to certain pronouns.

Modern Welsh can be written in two varieties – Colloquial Welsh or Literary Welsh. The grammar described on this article is for Literary Welsh.

The morphology of the Welsh language has many characteristics likely to be unfamiliar to speakers of English or continental European languages like French or German, but has much in common with the other modern Insular Celtic languages: Irish, Scottish Gaelic, Manx, Cornish, and Breton. Welsh is a moderately inflected language. Verbs inflect for person, number, tense, and mood, with affirmative, interrogative, and negative conjugations of some verbs. There is no case inflection in Modern Welsh.

Modern Welsh can be written, and spoken, in several levels of formality, for example colloquial or literary, as well as different dialects. The grammar described in this article is for Colloquial Welsh, which is used for speech and informal writing. Literary Welsh is closer to the form of Welsh used in William Morgan's 1588 translation of the Bible and can be seen in formal writing. It does not reflect the spoken language presented here.

Irish (Standard Irish: Gaeilge), also known as Irish Gaelic or simply Gaelic (/ˈɡeɪlɪk/ GAY-lik), is a Celtic language of the Indo-European language family that belongs to the Goidelic languages and further to Insular Celtic, and is indigenous to the island of Ireland. It was the majority of the population's first language until the 19th century, when English gradually became dominant, particularly in the last decades of the century, in what is sometimes characterised as a result of linguistic imperialism.

Today, Irish is still commonly spoken as a first language in Ireland's Gaeltacht regions, in which 2% of Ireland's population lived in 2022.

Gaulish is an extinct Celtic language spoken in parts of Continental Europe before and during the period of the Roman Empire. In the narrow sense, Gaulish was the language of the Celts of Gaul (now France, Luxembourg, Belgium, most of Switzerland, Northern Italy, as well as the parts of the Netherlands and Germany on the west bank of the Rhine). In a wider sense, it also comprises varieties of Celtic that were spoken across much of central Europe ("Noric"), parts of the Balkans, and Anatolia ("Galatian"), which are thought to have been closely related. The more divergent Lepontic of Northern Italy has also sometimes been subsumed under Gaulish.

Together with Lepontic and the Celtiberian spoken in the Iberian Peninsula, Gaulish is a member of the geographic group of Continental Celtic languages. The precise linguistic relationships among them, as well as between them and the modern Insular Celtic languages, are uncertain and a matter of ongoing debate because of their sparse attestation.

Irish (Standard Irish: Gaeilge), also known as Irish Gaelic or simply Gaelic (/ˈɡeɪlɪk/ GAY-lik), is a Celtic language of the Indo-European language family that belongs to the Goidelic languages and further to Insular Celtic, and is indigenous to the island of Ireland. It was the first language of the majority of the population until the 19th century, when English gradually became dominant, particularly in the last decades of the century, in what is sometimes characterised as a result of linguistic imperialism.

Today, Irish is still commonly spoken as a first language in Ireland's Gaeltacht regions, in which 2% of Ireland's population lived in 2022.

The Continental Celtic languages are the now-extinct group of the Celtic languages that were spoken on the continent of Europe and in central Anatolia, as distinguished from the Insular Celtic languages of the British Isles, Ireland and Brittany. Continental Celtic is a geographic, rather than linguistic, grouping of the ancient Celtic languages.

These languages were spoken by the people known to Roman and Greek writers as the Keltoi, Celtae, Galli, and Galatae. They were spoken in an area arcing from the northern half of Iberia in the west to north of Belgium, and east to the Carpathian basin and the Balkans as Noric, and in inner Anatolia (modern day Turkey) as Galatian.

The Brittonic languages (also Brythonic or British Celtic; Welsh: ieithoedd Brythonaidd/Prydeinig; Cornish: yethow brythonek/predennek; and Breton: yezhoù predenek) form one of the two branches of the Insular Celtic languages; the other is Goidelic. It comprises the extant languages Breton, Cornish, and Welsh. The name Brythonic was derived by Welsh Celticist John Rhys from the Welsh word Brython, denoting a Celtic Briton as distinguished from Anglo-Saxons or Gaels.

The Brittonic languages derive from the Common Brittonic language, spoken throughout Great Britain during the Iron Age and Roman period. In the 5th and 6th centuries emigrating Britons also took Brittonic speech to the continent, most significantly in Brittany and Britonia. During the next few centuries, in much of Britain the language was replaced by Old English and Scottish Gaelic, with the remaining Common Brittonic language splitting into regional dialects, eventually evolving into Welsh, Cornish, Breton, Cumbric, and probably Pictish. Welsh and Breton continue to be spoken as native languages, while a revival in Cornish has led to an increase in speakers of that language. Cumbric and Pictish are extinct, having been replaced by Goidelic and Anglic speech. There is also a community of Brittonic language speakers in Y Wladfa (the Welsh settlement in Patagonia).