A check-in is an act of checking into a location and sharing that information. The term is often also used as a verb, to check in.
Services like Foursquare are social community sites specifically designed for sharing check-ins.
Apple Quaker Bridge.
40° 17.494 N -74° 40.88 W
The Falafel House.
First time here. Was greeted warmly. Having the lamb burger.
40° 30.338 N -74° 38.512 W
At Aja (Montgomery) celebrating my daughter’s 18th. I have two adult children.
40° 25.256 N -74° 39.339 W