What does a Wild Card in Tennis mean?

A good example is the recent handing of a wild card to Naomi Osaka to play at BNP Paribas Open  in Match. Since her hiatus from tennis last year after a knockout in the US Open, Osaka’s WTA ranking dived to 84.

Around eight wildcards will be given out at Grand Slam tournaments.

Wild Cards are given in swimming and track and field competitions at the Olympic and World Championship level.

HOW DOES ONE QUALIFY FOR A WILD CARD?