护照 (hùzhào): A 护照 is an official government document that certifies one's identity and citizenship. It is required when applying for a 签证.
入境 (rùjìng): 入境 means "to enter into" or "to come into." It refers to the act of entering another country with proper documentation such as a valid passport and 签证.
出境 (chūjìng): 出境 means "to exit" or "to leave." It refers to the act of leaving one's own country and going abroad, usually requiring valid travel documents including passports and visas.