The Area Control mechanic typically awards control of an area to the player that has the majority of units or influence in that area. As such, it can be viewed as a sub-category of Auction/Bidding in that players can up their "bids" for specific areas through the placement of units or meeples.
In El Grande, for instance, players earn their score in a region by having the most caballeros in that region.
A real life example is football/soccer where area control is paramount even if the chains are in constant motion back and forth. There might not be a direct area control reward in form of victory points to score for holding XYZ, but the lack of area control can quickly lead to a missed opportunity to yourself or a goal opportunity to your opponent.