Alaska (/əˈlæskə/ (About this soundlisten); Aleut: Alax̂sxax̂; Inupiaq: Alaasikaq; Pacific Gulf Yupik: Alas'kaaq; Tlingit: Anáaski) is a U.S. state on the northwest extremity of the country's West Coast, just across the Bering Strait from Asia. A semi-exclave of the U.S., it borders the Canadian province of British Columbia and territory of Yukon to the east and southeast and has a maritime border with Russia's Chukotka Autonomous Okrug to the west. To the north are the Chukchi and Beaufort seas of the Arctic Ocean, while the Pacific Ocean lies to the south and southwest.

Alaska is by far the largest U.S. state by area, comprising more total area than the next three largest states Texas, California, and Montana combined, and the seventh-largest subnational division in the world. It is the third-least populous and the most sparsely populated state, but by far the continent's most populous territory located mostly north of the 60th parallel, with an estimated population of 738,432 as of 2015—more than quadruple the combined populations of Northern Canada and Greenland. Approximately half of Alaska's residents live within the Anchorage metropolitan area. The state capital of Juneau is the second-largest city in the United States by area, comprising more territory than the states of Rhode Island and Delaware.

Alaska was occupied by various indigenous peoples for thousands of years before the arrival of Europeans. The state is considered the entry point for the settlement of North America by way of the Bering land bridge. The Russians were the first Europeans to settle the area beginning in the 18th century, eventually establishing Russian America, which spanned most of the current state. The expense and difficulty of maintaining this distant possession prompted its sale to the U.S. in 1867 for US$7.2 million, or approximately two cents per acre ($4.74/km2). The area went through several administrative changes before becoming organized as a territory on May 11, 1912. It was admitted as the 49th state of the U.S. on January 3, 1959.

While it has one of the smallest state economies in the country, Alaska's per capita income is among the highest, owing to a diversified economy dominated by fishing, natural gas, and oil, all of which it has in abundance. United States armed forces bases and tourism are also a significant part of the economy; more than half the state is federally owned public land, including a multitude of national forests, parks, and wildlife refuges.

Alaska's indigenous population is proportionally the highest of any U.S. state, at over 15 percent. Close to two dozen native languages are spoken, and Alaskan Natives exercise considerable influence in local and state politics.

Alaska is the northernmost and westernmost state in the United States and has the most easterly longitude in the United States because the Aleutian Islands extend into the Eastern Hemisphere. Alaska is the only non-contiguous U.S. state on continental North America; about 500 miles (800 km) of British Columbia (Canada) separates Alaska from Washington. It is technically part of the continental U.S., but is sometimes not included in colloquial use; Alaska is not part of the contiguous U.S., often called "the Lower 48". The capital city, Juneau, is situated on the mainland of the North American continent but is not connected by road to the rest of the North American highway system.

The state is bordered by Canada's Yukon and British Columbia to the east (making it the only state to border a Canadian territory), the Gulf of Alaska and the Pacific Ocean to the south and southwest, the Bering Sea, Bering Strait, and Chukchi Sea to the west and the Arctic Ocean to the north. Alaska's territorial waters touch Russia's territorial waters in the Bering Strait, as the Russian Big Diomede Island and Alaskan Little Diomede Island are only 3 miles (4.8 km) apart. Alaska has a longer coastline than all the other U.S. states combined. Alaska's size compared with the 48 contiguous states (Albers equal-area conic projection)

At 663,268 square miles (1,717,856 km2) in area, Alaska is by far the largest state in the United States, and is more than twice the size of the second-largest U.S. state, Texas. Alaska is the seventh largest sub-national division in the world, and if it was an independent nation would be the 19th largest country in the world.