The ship inventory is a hud element in Lightspeed Frontier that allows the player to browse items in cargo and nearby modules. When player takes out a module out of the inventory, the building system enters continuous building mode.
Those allow you to faster find the module you're looking for.Toggle between everything and nothing. Command Pods Armor modules. Weapons Reactors Engines Cargo Containers Utility modules. The rest of items that don't fit any any other category.