Michael Alexander Kirkwood Halliday (often M. A. K. Halliday; 13 April 1925 – 15 April 2018) was an English-born linguist who developed the internationally influential systemic functional linguistics (SFL) model of language. His grammatical descriptions go by the name of systemic functional grammar. Halliday described language as a semiotic system, "not in the sense of a system of signs, but a systemic resource for meaning". For Halliday, language was a "meaning potential"; by extension, he defined linguistics as the study of "how people exchange meanings by 'languaging'". Halliday described himself as a "generalist", meaning that he tried "to look at language from every possible vantage point", and has described his work as "wander the highways and byways of language". But he said that "to the extent that I favoured any one angle, it was the social: language as the creature and creator of human society".