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.

Baybayin is a Philippine script. The script is an abugida belonging to the family of the Brahmic scripts. Geographically, it was widely used in Luzon and other parts of the Philippines prior to and during the 16th and 17th centuries before being replaced by the Latin alphabet during the period of Spanish colonization. It was used in the Tagalog language and, to a lesser extent, Kapampangan-speaking areas; its use spread to the Ilocanos in the early 17th century. In the 19th and 20th centuries, baybayin survived and evolved into multiple forms—the Tagbanwa script of Palawan, and the Hanuno'o and Buhid scripts of Mindoro—and was used to create the constructed modern Kulitan script of the Kapampangan and the Ibalnan script of the Palawan people. Under the Unicode Standard and ISO 15924, the script is encoded as the Tagalog block.