Any planet you discover on your journey is marked on your galactic map, along with its name, its atmosphere and what resources you found there. If you choose to, you can then share that information with every other player, uploading it so that it’s shared across everyone’s galactic map.
You’ll get credit for discovering it. You’ll also, if the materials there are valuable, attract players to come visit. No Man’s Sky isn’t a multiplayer game, in as much as you’ll never see another player. But the galaxy is the same between everyone and actions of “significance” will be shared. If you kill a single bird, that won’t be shared. If you make an entire species of bird extinct, then those creatures will blink out of existence for everyone.
That means you might want to keep quiet about a planet of valuable resources, so others don’t come and deplete it. I also instantly start thinking of ways to be devious. Can I upload false information to the galactic map? Can I lure people to a system full of pirates and then, when their ships crash and burn, steal materials from their ghostly hulls?