Doobieous is entirely correct.
For those who really want to know a LOT about the letter C, it has its origins in the Phoenician letter Gimel (where the meaning of the lettername is camel, and the pronunciation is a hard G as in gum), which the Greeks, when they adopted the alphabet (around 700BC), called gamma (looks like a y in lowercase (ã), uppercase looks like an upsidedown L (Ã)), also pronounced as a hard /G/.
Now, the Etruscans (a people living in central Italy, controlling modern Tuscany and, for lengthy periods, Rome – they spoke a language that is only partially deciphered and not convincingly related to any other known tongue) borrowed it around 600-500 BC, but it so happened that in their language, there was no sound like the hard /G/ in gum, so they just used the letters à (gamma) and K interchangeably to represent the sound /K/, coming to prefer the former…
Only thing was, their form of the letter gamma was curved, and in fact looked like this: C.
So when the Romans started writing their own language (Latin) in about the 4th century BC, they had a choice of two letters (C and K) both with the sound /K/, but no letter to represent the hard /G/ sound, which DID exist in Latin.
So for a while to represent the sound G they used the letter C… but they were clever buggers and eventually added a small stroke to the letter C to make sure that people knew it was to be pronounced as a /G/ instead.
Meanwhile, they were pretty much discarding the letter K, which survives only in a few words like Kalendae… but during all this time they were continuing to pronounce C as a hard /K/ sound.
This is where Doobieous’s part of the story comes in… for those who want a more detailed account of the further exciting adventures of the letter C, I’ll give you my address and you can mail me $10.
Though I will mention that the only modern European languages where the letter C retains its classical Latin pronunciation are Irish, Welsh and Scots Gaelic. We Celts don’t mess with a good thing.