Can I transfer my Terraria world from one PC to another?

Solution 1:

Yes, if you wish to have both worlds on your PC (assuming that's the destination computer), you need to rename the transferred file to "world2.wld". Otherwise, the older one will be replaced by the newer one.

Solution 2:

If you are looking to transfer player files to another PC, the player files are in the a similar area to the world files. If your world files are in \Terraria\Worlds, then your player files are in \Terraria\Players. (At least they are this way on Vista.) The files are named like the worlds... Player1.plr, Player2.plr, ect. Don't forget to back up the files before messing around, for example make a copy of the Players and Worlds directory (or at least the files you want to work with) before copying.