C-3PO is humanoid droid designed to interact with any living organism, normally for communication. He is fluent in 6 million different forms of language, however his personality changed over the years to fussy and being very worry-prone. C-3PO was rebuilt after he was destroyed on the planet Tatooine and because he was salvaged, this game him special qualities which made him stand out compared to his droid counterparts. C-3PO, accompanied by his counterpart R2-D2 astromech droid, were present at many pivitol monets in the Galaxy's history.
C-3PO started as a droid serving the Manakron System, however 80 years later he was thrown away only to be rebuilt by a young Anakin Skywalker. 10 years later C-3PO helped Anakin to win the pod race and leave Tatooine. When Anakin's mother died, C-3PO was gifted to him, now a Jedi Padawan. Soon C-3PO/R2-D2 got involved in the Clone wars, which was fought between the Galatic Republic and the Separatist Confederacy of Independent Systems. At the end of the war, anakin became a Sith Lord and C-3POs memory was wiped.
He later served the Rebel Alliance, helping R2-D2 complete his mission to deliver Death Star plans to the Rebel HQ. He went on to be a big help in the fight against the Empire, especially when it came to communicating with the warrior tribe of Ewoks on Endor.