The general valuation of rateable property in Ireland is a vital resource for those researching their Irish ancestors.  Apart from several fragments and transcripts, no extensive census information is available prior to 1901.  The results of the comprehensive valuation, ‘more commonly known by the eponym Griffith’s valuation, in deference to its chief architect and director Sir Richard Griffith (1784-­1878) … listed every occupier of property, the immediate lessor, acreage held, type of buildings occupied and value of the property.’  Griffith's Valuation was published between 1847 and 1864 in a series of approximately 300 volumes and is free to search on Askaboutireland, but what do the numbers, letters and other oddities mean.  Hopefully, this page will answer that question.  If you want to read more about the genesis of the valuation click here.