Who owns the gates at airports?

Could you clarify for me who exactly holds the ownership rights to the gates at airports? Are they under the direct control of the airport authority, or are they leased out to individual airlines? Is there a standard practice in the industry as to who owns and operates these gates, or does it vary from airport to airport? I'm particularly interested in understanding the legal and operational aspects of gate ownership, and how it impacts the overall functioning of the airport.