Maps generated in other players' games can be downloaded by the player and opened in his or her copy of the game.
Saved worlds are stored in different locations depending on the operating system. It is currently not possible to select where the Minecraft data folder, and thus the saved worlds folder, is stored.
Prior to Beta 1.3, there were five world slots, and custom names were not possible. To use more than five worlds then, it was required to rename and move folders. This is no longer necessary; there can be theoretically any number of worlds, each with their own names.
 Locating Saved Worlds
 Any OS
- Open the game.
- Click on Options
- Click on Resource Packs
- Click Open resource pack folder.
- Go one directory level up (the folder you named your game profile).
- Enter the folder named Saves.
Note: this does not work on older versions of Mac OS X.
In Windows Explorer, type in the address bar %appdata%\.minecraft\saves\ and hit ↵ Enter or press the shift key . Alternatively this can be entered in the Run dialogue box (Start > Run... or Windows+R) or the searchbar in the startmenu. To open the folder from the searchbar you need to hit ↵ Enter.
While in finder go to Go -> Go to Folder or press ⌘ Command + ⇧ Shift + G then enter ~/Library/Application Support/minecraft/saves. or go in finder at the top hit and option then go to library then application support and then go to your Minecraft folder
Type ~/.minecraft/saves/ in your file manager's address bar, or in the terminal type cd ~/.minecraft/saves.