Celts
Developing out of the late-Neolithic (proto-Celtic) Beaker peoples, the diverse cultures of the Celts covered most of Europe from during the Ancient era before, but by tenth century AD they had evolved and merged with others so much there were no 'Celts' left.
More top quality content from the BBC, this time a series of animated and interactive stories explaining all about Celtic life and culture in the UK, via experiences such as 'Build a Hill Fort' or 'Design a Torc'. This is especially suitable for children.
The information you'll find here might not be any more detailed or accurate than that of my other links, but the use of keywords to create a Celtic crib sheet makes this potentially very useful.
Richard Hooker’s article on the Celts, provided by the dependable Washington State University, is an insightful and academic look at life, society and history across early Europe.
The tone of this short – some would say revisionist - article is sharp and honest, effectively debating how ancient people thought of themselves and whether the word 'Celt' is misused by historians. This is not the mythologising of elsewhere.