15. A non-transitory machine-readable medium storing a set of instructions that, when executed by one or more processors of a machine, cause the machine to perform operations to improve exposures of listings of items stored in one or more databases of an electronic commerce system across a plurality of front-end taxonomies associated with a plurality of subsystems of the electronic commerce system, the operations comprising: identifying that a listing of an item is exposed to a plurality of users of a first subsystem of the plurality of subsystems via a set of categories of a first front-end taxonomy of the plurality of front-end taxonomies, the first front-end taxonomy being associated with the first subsystem, the listing associated with a first inventory, the first inventory associated with the first subsystem; mapping the listing of the item to a set of categories of a global back-end taxonomy of the electronic commerce system, the global back-end taxonomy being maintained independently of the first front-end taxonomy and a second front-end taxonomy of the plurality of front-end taxonomies, the second front-end taxonomy being associated with a second subsystem of the plurality of subsystems, the mapping of the listing based on a product type of the listing; mapping a category of the set of categories of the global back-end taxonomy to a category of a set of categories of the second front-end taxonomy associated with the second subsystem, the mapping of the category based on the product type and a most common classification of other listings associated with a second inventory, the second inventory associated with the second subsystem; and exposing the listing of the item to a plurality of users of the second subsystem via the set of categories of the second front-end taxonomy based on the mapping of the listing of the item to the set of categories of the global back-end taxonomy and the mapping of the set of categories of the global back-end taxonomy to the category of the second front-end taxonomy, the exposing allowing a user of the second subsystem to access the listing associated with the first inventory from a user interface of the second subsystem.
15. A non-transitory machine-readable medium storing a set of instructions that, when executed by one or more processors of a machine, cause the machine to perform operations to improve exposures of listings of items stored in one or more databases of an electronic commerce system across a plurality of front-end taxonomies associated with a plurality of subsystems of the electronic commerce system, the operations comprising: identifying that a listing of an item is exposed to a plurality of users of a first subsystem of the plurality of subsystems via a set of categories of a first front-end taxonomy of the plurality of front-end taxonomies, the first front-end taxonomy being associated with the first subsystem, the listing associated with a first inventory, the first inventory associated with the first subsystem; mapping the listing of the item to a set of categories of a global back-end taxonomy of the electronic commerce system, the global back-end taxonomy being maintained independently of the first front-end taxonomy and a second front-end taxonomy of the plurality of front-end taxonomies, the second front-end taxonomy being associated with a second subsystem of the plurality of subsystems, the mapping of the listing based on a product type of the listing; mapping a category of the set of categories of the global back-end taxonomy to a category of a set of categories of the second front-end taxonomy associated with the second subsystem, the mapping of the category based on the product type and a most common classification of other listings associated with a second inventory, the second inventory associated with the second subsystem; and exposing the listing of the item to a plurality of users of the second subsystem via the set of categories of the second front-end taxonomy based on the mapping of the listing of the item to the set of categories of the global back-end taxonomy and the mapping of the set of categories of the global back-end taxonomy to the category of the second front-end taxonomy, the exposing allowing a user of the second subsystem to access the listing associated with the first inventory from a user interface of the second subsystem. 17. The non-transitory machine-readable medium of claim 15 , wherein the item is one of a plurality of items listed on the electronic commerce system, and wherein a plurality of nodes of the global back-end taxonomy correspond to a plurality of product types associated with the plurality of items.