When dynamic changes occur to content on a page they are usually visually apparent to users who can see the page but may not be made apparent to users of assistive technologies. ARIA live regions provide a way to make those dynamic content changes able to be announced by assistive technologies.
aria-live: the priority with which updates are read
aria-atomic: whether the screen reader should always present the live region as a whole, even if only part of the region changes
aria-relevant- takes a list of what type of changes should be announced