The British decimal ten pence (10p) coin - often pronounced ten pee - is a unit of currency equaling ten one-hundredths of a pound sterling. The circulating coins went through a few transformations: initially, they were large, with dimensions equivalent to the pre-decimal two shilling (florin) coin, and featured a crowned lion reverse; in 1992 this was changed to a smaller 10p coin, retaining the same design.
In 2008 though the reverse was changed to Matthew Dent's design; in a world-first concept, the designs for the 1p, 2p, 5p, 10p, 20p and 50p coins depict sections of the Royal Shield that form the whole shield when placed together (the shield in its entirety being featured on the £1 coin).
Starting from 2012, the 10p coin was changed from cupro-nickel to nickel-plated steel.
During all this time, the denomination was only used to issue regular circulating coins. In 2018 however, the Royal Mint made history by starting a "coin hunt" when it issued the 10p A-Z Collection - a series of circulating commemorative coins, each featuring a letter of the alphabet and a British Heritage symbol with a name starting with that letter. Due to their very low mintage, these are avidly collected by the public though and do not, strictly speaking, circulate in any realistic manner.
The 10p coin is legal tender for amounts up to £5.