A deliberate exception to the ranking rule
Tournament entry is normally decided by ranking, but organisers reserve a small number of spots to invite players who would not otherwise qualify, whether because a ranking has fallen due to injury, a young player has not yet accumulated enough points, or a name is expected to draw significant local interest. This is a deliberate exception to an otherwise mechanical system, and tournaments use it sparingly precisely because handing it out too freely would undermine the fairness of the ranking-based system it sits alongside.
Who tends to receive them
In practice, wildcards cluster around a few recognisable categories: promising players from the host country who boost ticket sales and broadcast interest, well-known players returning from injury who need match play at a level their fallen ranking no longer guarantees, and occasionally a player whose recent form suggests they are underranked relative to their current ability. None of these criteria are about pure entitlement; they reflect a tournament balancing sporting fairness against its own commercial and promotional needs.
Why one entry can matter so much
For a player sitting just outside the ranking required for direct entry, a single wildcard can be disproportionately valuable, offering a chance to earn ranking points at a level of tournament their ranking alone would not have reached, which can then compound into further direct entries without needing another favour. This is why a wildcard, though it looks like a minor administrative gesture, is regularly discussed by players and agents as a genuine strategic asset worth actively pursuing.