Tagalog is an Austronesian language spoken as a first language by the ethnic Tagalog people, who make up a quarter of the population of the Philippines, and as a second language by the majority. Its standardized form, officially named Filipino, is the national language of the Philippines, and is one of two official languages, alongside English. Tagalog is closely related to other Philippine languages, such as the Bikol languages, the Bisayan languages, Ilocano, Kapampangan, and Pangasinan, and more distantly to other Austronesian languages, such as the Formosan languages of Taiwan, Indonesian, Malay, Hawaiian, Māori, Malagasy, and many more.

Tagalog is the first language of most Filipinos and the second language of most others. It is the native tongue of the people in the Tagalog region in the Philippines. The word Tagalog is derived from the endonym taga-ilog ("river dweller"), composed of tagá- ("native of" or "from") and ilog ("river") .

Filipino and Tagalog are varieties or dialects of the same language, and they share a big bulk of common lexical items and they have very similar grammatical structures. Filipino is essentially Tagalog, and it is the national language of the Philippines. Tagalog is more than just a language, it is a big part of the daily lives of Filipinos, and it is used in government, education, and media.