Button
Buttons trigger an action, such as submitting a form, closing a dialog, or navigating to a new page.
Use the aria-label attribute to provide alternative text for icon-only buttons. This text is read by screen readers and lets the user know the purpose of the button.
When using the button in a pending state, provide a label or aria-label to describe what is happening. Eg. 'Loading more search results'.
Disabled buttons don't explain why the button isn't usable, and they aren't focusable at all for people using keyboard navigation.
Instead, keep the button pressable, and use validation and errors to explain what needs to be done to proceed.
Tooltips can't be reached on all devices or by some assitive technologies, and they should never appear on elements that aren't interactable.