What is Haplontic, diplontic, haplo-diplontic?

Every sexual life cycle contains one fertilisation, which doubles the chromosome number, and one meiosis, which halves it; the cycles differ in what happens between them. In a haplontic cycle the zygote is the only diploid cell and undergoes meiosis at once; the organism is haploid and its gametes are made by mitosis (Chlamydomonas, many algae and fungi). In a diplontic cycle meiosis makes gametes directly, the gametes are the only haploid cells, and the organism is diploid (animals, the brown alga Fucus). In a haplo-diplontic cycle meiosis makes spores, which grow by mitosis into a haploid organism, the gametophyte, that makes gametes by mitosis; the zygote grows by mitosis into a diploid organism, the sporophyte, that makes spores by meiosis. Two multicellular bodies alternate — the alternation of generations — and this is the cycle of every land plant and of many algae.