*mark on the right side of the title.
*mark disappears. Even though you forgot to save, you can recover the unsaved contents when you login in next time. However, to keep your code safe, don't forget saving the code before you leave.
Ctrl + S (Mac: ⌘S).
Ctrl + Shift + S (Mac: ⌘⇧S).
Alt + Ctrl + S (Mac: ⌥⌘S)to save all currently opened editors at once.