That was very likely Street Complete which is self explanatory and a great way to start. You are adding all kinds of useful information about any kind of object or building with this.
There’s also Vespucci which allows to alter the whole map (ie edit streets, POIs and so on) but takes a lot more to get familiar with.
I once saw a comment about an app that made it easier to contribute to OSM. Do you know which one that might be?
That was very likely Street Complete which is self explanatory and a great way to start. You are adding all kinds of useful information about any kind of object or building with this.
There’s also Vespucci which allows to alter the whole map (ie edit streets, POIs and so on) but takes a lot more to get familiar with.
You can also try the webapp https://mapcomplete.org
Honorable mention for Maproulette as well!