Golden Strawberries are special berries, tinted gold in color and with a crown on top, which are first unlocked upon completing Core B-Side. After being unlocked, they appear at the start of every chapter, with the exception of 6A, 8 (all sides) and 9. They are only collected at the last screens of the chapter in A-sides and upon collecting a heart in B-sides and C-sides.
Upon picking one up, the player must finish the entire chapter without dying in order to collect it. Dying at any point within the chapter will result in both the loss of the berry and the player being teleported back to the room where they first obtained it.
Golden Strawberries are meant to be some of the most difficult challenges in Celeste. The only differences that appear within Celeste upon the collection of a golden strawberry are aesthetic ones, most notably the level select gaining a golden tint (for the specific side). Obtaining 202 strawberries will give the entire save file (in the save select) a gold-tinted background. Prior to the addition of Farewell, there were 200 strawberries in total.
The easiest golden strawberry is generally accepted to be the one in Forsaken City A-Side. This is followed by Old Site A-Side, as well as the C-Sides, owing to their short length. The B-Sides are generally the hardest, because they bring both length and difficulty. Farewell, being significantly longer and more difficult than any of the other levels, is by far the hardest.
Unlike practicing for speedruns, obtaining a Golden Strawberry is all about consistency, and being able to make it across a large number of rooms without dying once. Each level here on the Celeste Wiki will have a guide with strategies on collecting Golden Strawberries. However, doing as such usually will not yield it on the first attempt; keep trying, practice makes perfect.
A winged golden strawberry exists in Celeste; however, it is unrelated to the other Golden Strawberries. This winged golden strawberry, instead of requiring completing a level without dying, requires completing Forsaken City A-Side without dashing at all.