What crimes does the president need to commit to become impeached?

The exact definition of impeachable offense set by House of Representatives when a bill of impeachment is presented for debate and a vote. Surely any clear violation of federal law, such as treason, accepting bribes, obstructing justice or lying under oath would qualify as cause for impeachment, but other conduct unbecoming to a president could also be grounds. If the president's behavior is an outrage to most of the country, even if it may be legal. the House could consider impeachment.