Irish or Gaelic was a strong and flourishing language for many centuries after the coming of cristianity to Ireland.Irish scolars learned the Latin of the monks and used the Latin alphabet to write down Irish words.The Latin alphabet had only 18 letters while there were at least 60 sounds in Gaelic,so it was not an easy job.Mordern Irish is made even more complex because over the centuries the pronunciation of words has changed while the spelling has remained the same.Just as learned of English have trouble with words like "through",so lerners of Irish must deal with words such as leabhar("leer"),maening book,or gadhar("gair"),which means dog.
Irish is an inflected language,that is,the spelling of the words varies depending how they are used in a sentance.So the Irish for "cat" can be spelled as cat,cait,chat,gcat,orgcait,depending on the intended meaning.Another difficulty for aspiring Irish speakers!