According to Wikipedia,
Michael Alexander Kirkwood Halliday was a British linguist who developed the internationally influential systemic functional linguistics 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[ing] 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".
Michael Halliday is affiliated with the following schools: