Bitcoin transactions are not tied to any personal information which allows users to protect their privacy. However, since all Bitcoin transactions are public knowledge and permanently on the blockchain, other users can see the activity associated to a particular wallet address—hence not being 100% anonymous. It is highly recommended to only use Bitcoin addresses once to avoid your identity being revealed either through a specific purchase or other means.
New to Bitcoin? Check out CoinGeek’s Bitcoin for Beginners section, the ultimate resource guide to learn more about Bitcoin—as originally envisioned by Satoshi Nakamoto—and blockchain.