Hint: Think about what align-items on the container actually controls — the alignment of one single item, or every item within that container collectively.

align-items is specifically a property of the flex container itself, and it sets one single alignment value that's applied uniformly to every flex item within that container at once, it has no built-in mechanism at all for specifying different alignment values for different individual items, since it's fundamentally a container-level, all-items-at-once setting rather than something that can target specific children individually. align-self exists specifically to fill exactly that gap, providing a way to set an alignment value directly on one individual flex item, overriding whatever the container's align-items would otherwise apply to just that one specific item, while leaving every other sibling item completely unaffected and still following the container's original align-items value normally. Without align-self, achieving a single item's different alignment would require restructuring the layout entirely, perhaps wrapping that one item in its own separate nested flex container just to give it independent alignment control, which would be considerably more cumbersome than simply setting one targeted property directly on the item that actually needs to behave differently from its siblings.