Google syncs all of your activity across its many platforms into one detailed user profile that shows who you are, what you do and what you like. It then uses this information to improve its services, along with targeting its advertising to your preferences. While Google does track quite a bit of your Web usage, your YouTube viewing history is not publicly available. If you work on a shared computer or let others use your PC, clearing your viewing history may be a good way to protect your privacy.
