People often want to know what the difference is between Tagalog and Filipino. However, asking that question is a bit of a misnomer because Tagalog is actually the basis for the Philippine national language.
Tagalog had primarily been spoken in Manila and the surrounding provinces in the 1930s when the Commonwealth Constitution was originally drawn up. This constitution had stipulations in it that provided for an official national language, but it did not specifically name Tagalog as that language. When the constitution was drawn up, Tagalog was only spoken by about 25% of the population.
Tagalog was the lingua franca of people who lived in or near the government capital, and by the 1970s, more than half of the Philippine population was using Tagalog to communicate with one another.
Then, during the Aquino presidency in the latter half of the 1980s, the national language was officially labeled Filipino. The purpose of this was to embrace the widespread preference for a number of words derived from English and Spanish, as well as the incorporation of “Western” letters such as j, c, x, z, and f. These were not natural sounds to the native citizens of those islands before the arrival of foreigners from Spain and the Americas, but they quickly became a part of the Filipino alphabet.
Filipino has incorporated a number of modern words from English and Spanish. For example, the Spanish word “diccionario” has been incorporated into Filipino as “diksyunaryio.” However, a Tagalog purist might insist on the native word for dictionary, which is “talatinigan.”
Language is a fluid and ever evolving thing, and the evolution from Tagalog to Filipino is taught in schools throughout the region. So, when you ask someone the question, “What is the difference between Filipino and Tagalog?” the answer is that Tagalog is the foundation upon which Filipino was built, and Filipino is the natural evolution of Tagalog.
