What CSS property does the value flex-end belong to and when would you use it?

The value flex-end can be assigned to a CSS property justify-content or align-content.

The combination of justify-content: flex-end will move the flex items to the end of the main axis. You usually use it to align the horizontally flowing items to right or vertically flowing items to bottom.

The combination of align-content: flex-end will move the flex items to the end of the secondary (perpendicular) axis. You usually use it to align horizontally flowing items to bottom or vertically flowing items to right.

CSS

div {
  display: flex;
  justify-content: flex-end;
  align-content: flex-end;
}