CHECK IN can mean: register at a hotel / update how you are - When we arrived at the hotel, we checked in at reception. - Hey, I'm just calling to check in and see how you are. CHECK something OUT can mean: have a look at - Hey dude, this dog can do tricks! Check it out! - Mum, check this out! I got an A on my test!

It means reservation and departure

To expand, “check out” (without an object) means when you leave a hotel. For example: “You must check out of your room by 11am tomorrow.” It can also be used when you borrow something, such as from a library. Ex: “I checked out your favorite book from the library.” Lastly, it’s used when you finish shopping and pay, such as at a grocery store. Ex: “That’s everything, so I’m ready to check out.” One other note: “check in” is a verb, whereas the hyphenated version “check-in” can be used as either a noun or adjective. Ex: “Check-in is at 3pm” or “The check-in process is very simple.” Similarly, “check out” is a verb, while “checkout” is a noun or adjective. Ex: “Checkout is at 11am” or “The checkout line is very long.”