The backpack is a feature that gives a player the ability to use BackpackItems. This is one of the features that have existed since 2006. The backpack can be also used for scripting. There are also hotkeys that exist, numbered from 0 to 9.
In-experience inventory
The inventory displays BackpackItems that are not in the current loadout. The inventory opens when activating ` or the "Inventory" button in the Hamburger Menu, just like on Mobile.
History
The first recorded version its from 2011, when the Experience Controls where updated, they added a button leading to the inventory (called backpack back then) and as an alternative, the ` shortcut. Then later in 2012 updating it to be an arrow above the Backpack
The arrow shortcut was redesigned between late 2014 and Early 2015, later to be made the iconic backpack button in the Topbar, later to be put in the expanded menu.
Assets
There are 5 Lua CoreScripts which were used to build the backpack from June 2011 to 2014:
- BackpackBuilder
- BackpackResizer (Usage ended in 2012)
- LoadoutScript
- BackpackGear (Usage began in 2012)
- BackpackManager (Usage began in 2012)
2006 – 2009
The backpack in 2006 was very simplistic. This backpack could carry up to 10 BackpackItems; if a player had too many BackpackItems, they would begin to disappear. The only way to get extra BackpackItems was to drop 
Tools by pressing ← Backspace.
2009 – December 2010
When Gear was introduced in May 2009, Roblox administrators updated it so that a player could have up to around 30 BackpackItems. It was similar to the old backpack, in which extra tools would disappear.
December 2010 - June 2011
In December 2010, the style of the backpack changed.
June 2011 – August 2012
In June 2011, the backpack was updated, using CoreScripts instead of LocalBackpack, which allowed the player to access any tools beyond 30. The backpack also contained a search bar, which could search up any relative tool name. The backpack button was located to the left of the player's health bar.
August 2012 - November 2012
Slight style changes were made to the backpack and it took up more screen space when opened. It opened and closed faster.
November 2012 – 2014
In November 2012 they changed the backpack again with new styling and made the buttons transparent as well as moving the backpack button above the current loadout.
Late 2014
Towards the end of 2014 they changed the backpack to look more modern, removing the styling of it, and making things square, the backpack button became an arrow.
Early 2015
It is the same as the previous one but the backpack button box got filled in with a background and they upped the transparency and changed the font of the numbering.
Mid 2015 – present
The current backpack has no arrow, and features transparent squares for each BackpackItem. Up to 10 BackpackItems can be shown on the hotbar.