ESL

Expression : boot the PC [Personal Computer]


Cowboys wear long boots with "bootstraps" to pull on their boots
without help from another person.

There is an expression: "pull yourself up by your own bootstraps",
which means "be successful without any help from anyone else".
For example:
 "Barack Obama came from a poor family, but he pulled himself up by his own bootstraps".

The computer program that starts a computer is called the "bootstrap program" by programmers because it runs without any help from another program.

Then "bootstrap" was shortened to "boot".
So "Boot (your PC)" means "turn the PC on";
and "re-boot (your PC)" means "turn your PC off, and then turn your PC on again."