Minecraft Launcher

The Minecraft Launcher is the start-up for the game, Minecraft. Initially, the launcher displays updates on events, and when an update is available (which can be done automatically, or put on hold). There are several other features that can be found within the launcher. The current launcher is at 1.2.5, made for launching 1.7.10.

Features
The launcher features multiple selections, which can only be found in the most current Minecraft updates (updates 1.6 and later).

Time Machine
The "Time Machine" is a coined phrase used to describe the new feature that allows any user with the current launcher to access previous versions of the game. Compatible versions currently go back to the Beta releases, info about whether or not any Alpha releases are to be released is unknown. Worlds cannot be entered if created in 1.6, however, new ones can be created.

The time machine was created to explore the previous versions of the game. This is the only way that some users can access certain properties, such as duplicating items. The downside to the time machine is that bug-fixes are not implemented and are only found within the current version.

Profile Editor
The Profile Editor is a recently added option that allows a user to add other "profiles" to their account, that way multiple users can use the account. The downside to this is that it does not count as another account, meaning that only one person under the account can be on a server, be in a LAN world, etc.

However, it has been stated that there are plans to implement multiple users under one account (possibly Minecraft or Mojang) along with the new Username ID system, which identifies users under their fake "username" instead of their IP address.

Local Versions Access
The Local Version Editor is a set-up menu that allows the owner of an account to access the multiple profiles that he or she may have. This is used with the time machine to edit the version of a profile (i.e. Beta). This is intended for a user to have multiple profiles that they can use for a single period in the version history, so that worlds in more up-to-date versions are not corrupted by transporting them into previous versions.

Other Features
The launcher has the capabilities to be altered slightly by certain external Minecraft related programs, the most renowned program being OptiFine. The largest change only occurs through the use of profiles, which can become helpful for playing on worlds with a modification without ruining other worlds.