This list comprises a wealth index of current and active professional footballers, as measured by their identifiable wealth.
Those who qualify for the list include Fifa-registered professional players of all nationalities in any professional league across the world - or registered players currently without a club, but who are actively looking to sign for a professional outfit.
Although we have concentrated the published list on the top 10 earners in the world, a far larger pool of players was considered before the final selection.
We attempt to measure only identifiable assets including salaries, length of contract, bonuses, endorsement and sponsorship deals, properties and other business interests.
We have no access to bank accounts and do not attempt to compromise player privacy in any way. As a result, cash holdings in private accounts are not considered in this research and so actual wealth may vary from the figures we have concluded.
Business interests may include stakes in quoted companies. It is much more difficult valuing stakes in private companies. We try, as a general rule, to base valuations on the prevailing price/earnings ratio for a sector or an equivalent quoted company. Business interests under the name of a spouse or other family members cannot always be accounted for, but where this is possible these have been taken into account.
Most of the player information has been sourced from public and reputable sources. We have also used the expertise and knowledge of a number of player agents, marketing experts and club sources.
We have applied typical national tax rates for high-earners.
Transfer fees - payments to players
With regards to payments due to players following a transfer, we have worked on the premise that young footballers can receive on average between 10-15% of any profit the player's club makes on their transfer fee.
In the UK, very few footballers tend not to receive a percentage of their transfer fee, although this is negotiable on a player-by-player basis.
In Spain, Netherlands and other leading European countries, these fees are more common and are typically closer to 15% of fees received when they move to higher-profile leagues for large figures. British-based players can earn lump sums from transfers through their signing on fees.
The bonus figures we have quoted are basic bonuses for team success, but don't include individual signing-on fees, image rights or loyalty payments, unless otherwise stated.