In philosophy, what is the "Ship of Theseus"?

The "Ship of Theseus" is an excellent thought experiment. It ponders if an object is the same if all of its components are replaced over time.

In Greek mythology, Theseus, mythical king of the city Athens, rescued the children of Athens from King Minos after slaying the minotaur and then escaped onto a ship going to Delos. Each year, the Athenians would commemorate this by taking the ship on a pilgrimage to Delos to honour Apollo. A question was raised by ancient philosophers: After several hundreds of years of maintenance, if each individual piece of the Ship of Theseus were replaced, one after the other, was it still the same ship?

Hobbes comes up with an excellent response. If the parts of the ship that were replaced were saved and then put back into another ship, then you would have two of the same ship. So what he suggests that only the original parts on a ship are the original ship and the replaced parts are something else.

https://en.wikipedia.org/wiki/Ship_of_Theseus