You just put up an amazing 4 pitch arete climb tucked away in the woods. You draw a map on a napkin with a topo and hand it to your buddy who is eager to do the second ascent. Of course he gets lost and spends the day bushwacking through poison oak cursing your name and the gaddamned napkin, now a smeared mess in his hand. Back at the bar when you ask him about the route he just gives you a glare of contempt while scratching the rash now spreading over his arm.
Say hello to Trail Book. In leader mode, it will store a path while you make a bee line for your climb. Take pictures, speak and type directions at tricky spots along the way. You don’t need a data connection while you’re creating the map. When you get back home, upload your path to the online database and give your friend a link to this site and some key words to search on (like the climb name and area, or approximate location).
Your friend opens up Trail Book in follower mode and downloads your path onto his phone while he still has a data connection. He follows your directions with ease, getting alerts when nearing the notes you left and helpful nudges when straying too far from your trail. He arrives at the rock fresh and ready to climb. This time back at the pub he has a big grin on his face remembering that airy traverse into the finger crack.