Welsh isn't usually called "gaelic", so we often say Irish Gaelic, Scottish Gaelic and Welsh (and of course the interbreed of the first two, Ulster Scots). We have to start by saying that Welsh is very separate from the two forms of Gaelic. Scottish and Irish Gaelic are both members of the Goidelic branch of the Celtic language family, whereas Welsh is a Brittonic language, so they share about as much similarity as Spanish and Italian (in that they're both Insular Celtic, but of different families, just as Spanish and Italian are both Romance, but Spanish is Iberian and Italian is Italo-Dalmatian). English, meanwhile is a West Germanic language with Romance influences, so it has almost nothing to do with any of these three languages. There are very few loan words from any of the three of them into English, although British place names are often influenced by them. This is in contrast with, say, Spanish and Galician and Catalan, which are all similar and influence each other. Irish is by far the most spoken language of the three; it is an official language of the Irish Republic (and therefore of the EU). Some 2.2 million people in Ireland (out of 4.6 million population) can speak Irish to a fluent level, with 170,000 having it as their native language. I believe education in Irish is compulsory even in English-speaking schools in the ROI. Most native speakers are concentrated in the Gaeltacht in the rural west of Ireland. It's an important cultural language, possessing the oldest recorded written literature in western Europe. Welsh has undergone something of a resurgence in the last 20 years; 320,000 (12%) of Wales' population claim to be fluent in Welsh, It's also spoken to an extent in the English border towns, and all signage in Wales is in English and Welsh. For example, the police have "HEDDLU / POLICE" written on their uniforms. It's related to the rare Cornish language of south-west England and the Breton language spoken in north-west France.

Scottish Gaelic is by far and away the smallest of the three. It's spoken in the very far north reaches of Scotland - the Highlands and Islands - by about 60,000 (1.2% of population) people. It was never spoken in the south of Scotland (e.g. in Edinburgh) and so has remained confined to the north. It's not an official language of the UK or of Scotland, but in the far north there are still signs in Scottish Gaelic. However, Scotland is trying to bring back the language through education efforts in the north. It's related to the Manx language that's now (almost) extinct. Examples of the languages: English: All human beings are born free and equal in dignity and rights. They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood. Welsh: Genir pawb yn rhydd ac yn gydradd â'i gilydd mewn urddas a hawliau. Fe'u cynysgaeddir â rheswm a chydwybod, a dylai pawb ymddwyn y naill at y llall mewn ysbryd cymodlon. Scottish Gaelic: Tha gach uile dhuine air a bhreth saor agus co-ionnan ann an urram 's ann an còirichean. Tha iad air am breth le reusan is le cogais agus mar sin bu chòir dhaibh a bhith beò nam measg fhein ann an spiorad bràthaireil. Irish: Saolaítear na daoine uile saor agus comhionann ina ndínit agus ina gcearta. Tá bua an réasúin agus an choinsiasa acu agus dlíd iad féin d'iompar de mheon bráithreachais i leith a chéile.