Filipino is the national language of the Phillippines, and is based on Tagalog. Filipino is supposed to be "Tagalog plus", incorporating some Western and Spanish words. Originally, Tagalog was a language spoken in the Manila area. Other languages were spoken in other areas, but the use of Tagalog spread over the years, making it more acceptable as a basis for the national language. Filipino and Tagalog do not fit the model of a single language that has several dialects--versions of the language spoken by different groups. However, in the sense that Filipino is agreed to be the standard language (taught in school, etc.) then you could call Tagalog a dialect. Remember, "A language is a dialect with an army and a navy.