When I use my arrow keys, Vim changes modes, inserts weird characters in my document but doesn’t move the cursor properly. What’s going on?

There are a couple of things that could be going on: either you are using Vim over a slow connection or Vim doesn’t understand the key sequence that your keyboard is generating. If you are working over a slow connection (such as a 2400 bps modem), you can try to set the ‘timeout’ or ‘ttimeout’ option. These options, combined with the ‘timeoutlen’ and ‘ttimeoutlen’ options, may fix the problem. The preceding procedure will not work correctly if your terminal sends key codes that Vim does not understand. In this situation, your best option is to map your key sequence to a matching cursor movement command and save these mappings in a file. You can then “:source” the file whenever you work from that terminal.