What it is: a certificate attached to a public document by a government authority to verify its authenticity for use in another country. It is the simplified way to “legalize” a document between countries that are members of the Hague Apostille Convention.
What this means for you: with an apostille, a US document can be recognized in the Philippines without further authentication by the Philippines’ Department of Foreign Affairs or consulate. The apostille goes on top of a properly notarized document — the combo is the “golden ticket” for most Philippine transactions.
Where you get it in the US: for most states, the Secretary of State — in Illinois, the Illinois Secretary of State’s office, after the document has been notarized.
What documents typically need one: SPAs, affidavits, birth/marriage/death certificates (through the issuing vital-records office), school records, and court documents — anything a Philippine body wants to trust as genuine.
Watch out for: the order is notarize → apostille. You cannot apostille a plain document. And the apostille is only valid for Hague member countries — the Philippines has been a member since 2019, so the apostille path (not the old consular “red ribbon”) is now the standard.