Status matches let you leverage elite status you've already earned at one program to jump-start status at another — often via a short "challenge" period. There's no single live feed of active matches, since programs turn them on and off without notice, so use this as a reference for how matches typically work and which programs have historically run them, then check the current landing page before assuming one is live.
Submit proof of your current elite status (a screenshot or account summary), and the target program grants you trial status for a set window (commonly 90 days) — hit a spend or stay requirement during the trial and the status becomes "real" for the rest of the year.
Hotel programs (Marriott, Hilton, IHG, World of Hyatt) have historically run matches more consistently than US airlines, which do so less predictably.
Usually a screenshot of your current status level and membership number from the program you're matching from — requirements vary, so check the specific offer page.
Compare programs directly with the Hilton and Marriott elite status calculators.