The '''innate, immune system''' or '''nonspecific, immune system'''<ref>{{Cite web|title=Immune response: MedlinePlus Medical Encyclopedia|url=https://medlineplus.gov/ency/article/000821.htm|access-date=2021-11-07|website=medlineplus.gov|language=en}}</ref> is one of the two main immunity strategies (the other being the [[adaptive immune system]]) in [[vertebrate]]s. The innate immune system is an alternate defense strategy and is the dominant immune system response found in [[plant]]s, [[fungi]], [[prokaryote]]s, and [[invertebrate]]s (see [[#Beyond vertebrates|Beyond vertebrates]]).<ref name="Janeway">{{cite book | vauthors = Janeway C, Paul C, Travers M, Walport M, Shlomchik M | author-link = Charles Janeway | title = Immunobiology | edition = Fifth | publisher = Garland Science | year = 2001 | ___location = New York and London| url = https://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowTOC&rid=imm.TOC&depth=10| isbn = 0-8153-4101-6}}.</ref>
The major functions of the innate immune system are to:
