Before you can play on any Minecraft server, you need to come up with your own nickname. In the nickname can use the letters of the English (Latin) alphabet, numbers and underscore.
So, you came up with a nickname and have already found a suitable server for the game in our monitoring. Now run the client Minecraft, log into the network game, enter the ip address and connect to the server. You are in the game world, but can not move, and the chat requires you to some strange password. What to do?