A Finsta (short for "fake Instagram") is a secondary, private Instagram account that users create to share more candid, personal, or less polished content with a smaller, trusted group of followers, usually close friends.
Unlike a primary Instagram account, which may be carefully curated for public consumption, a Finsta is more informal and often used to post things the user might not want to share with a larger audience.
The term has become popular among teenagers and young adults who use Finstas to escape the pressure of maintaining a "perfect" online image.