WA is the two-letter postal abbreviation for the American state of Washington, in the far northwest corner of the United States — the state whose biggest city is Seattle. It is written, not spoken: you see it in addresses, on forms, in tables and on maps (Seattle, WA 98101), and when you read it aloud you say 'Washington'. Both letters are capitals and there are no full stops, because that is the style the US Postal Service set for all fifty states. The important thing here is which Washington. The United States has two famous places with that name: Washington State on the Pacific coast, and Washington, D.C., the capital city, which sits on the opposite side of the country and is not a state at all. Their abbreviations are different — WA for the state, DC for the capital — and Americans often say 'Washington State' out loud precisely to keep the two apart. If you are writing an address, choosing the wrong one sends your letter about 4,000 kilometres astray. Two smaller notes. In Australia, WA stands for Western Australia, so context decides which country you are in. And in Taiwan and much of Asia, people sometimes type WA informally to mean WhatsApp — that is chat slang, not standard English, and you should not use it in any formal writing.