SeaTac is a city located in southern King County, Washington, within the United States. It functions as an inner-ring suburb of Seattle and forms part of the broader Seattle metropolitan area. The name SeaTac derives from the Seattle–Tacoma International Airport's nickname, which itself is a portmanteau of Seattle and Tacoma. This administrative entity sits between Puget Sound to the west and the Duwamish and Green River valleys to the east.

Coast Salish peoples inhabited the Highline ridge and surrounding lowlands for thousands of years before European contact. The area was settled by European Americans in the mid-1850s, leading to small farming communities developing around Miller Creek. The construction of Seattle–Tacoma International Airport in 1942 transformed the region, drawing workers during World War II. Residents voted for incorporation on March 14, 1989, and the city officially incorporated in February 1990.

The city boundaries surround the Seattle–Tacoma International Airport, which occupies approximately three square miles of its ten-square-mile area. SeaTac includes the pre-incorporation communities of Angle Lake, Bow Lake, McMicken Heights, and Riverton Heights. The airport serves as the primary commercial aviation gateway for the Puget Sound region, hosting major airlines like Alaska Airlines and Horizon Air, whose headquarters are located within the city limits.

Most visitors access SeaTac primarily through the international airport, which is surrounded by a cluster of hotels and related businesses catering to travelers. The area features a concentration of airport-dependent commerce along Pacific Highway South, evolved from regional through-traffic patterns. While there are few traditional tourist attractions, the city offers access to North SeaTac Park, established on land converted from a noise buffer program in the late 1970s.

According to the 2020 census, SeaTac has a population of 31,454 residents. The local economy is robust, with over 900 licensed businesses generating approximately $3.7 billion in local sales and employing nearly 40,000 people. Transportation access includes Interstate 5, State Route 518, and Link light rail stations at SeaTac/Airport and Angle Lake, providing connections to the wider region.