There are currently 110 City of London Livery Companies, all of which are or were involved with a particular trade or craft. A full list of the Companies can be seen here.
The oldest Company is generally believed to be the Weavers’ Company who were granted their Royal Charter in 1155. The youngest Company is the Arts Scholars which received its Letters Patent from the Court of Aldermen in 2014.
In order to become a Livery Company, a Guild needs to satisfy the Court of Aldermen on a number of matters, including that it supports a profession, trade or craft that is not already represented, and that it has an endowment to support charitable and educational activity.
The majority of Companies still support their trade, craft or profession in one way or another even though they may no longer control it. Some Companies whose original craft has disappeared have adapted and support the modern equivalent – for example, the Fanmakers and air conditioning or the Horners and plastic.