But this is quite vague.
So: by popular demand (my mum) a quick guide.
The 25th amendment was ratified- i.e. became part of the US constitution in 1967. The amendment is basically about clarifying the presidential and vice presidential succession.
But this is quite vague.
Tyler took the oath and became president. This set a precedent.
But this was not spelled out in law. And there were some outstanding questions:
2. What if the president is unwell, or unable to perform his role for some other reason? How can that be managed?
It does a few things. First, it sets out in law that, yes, if a president dies (or resigns, or is removed from office), the VP becomes president.
BUT...