Ascomycotina is a phylum of fungi that includes more than 64,000 species. Some synonyms for Ascomycotina include sac fungi, ascomycetes, and saccharomycetes. These names are derived from the presence of specialized structures called asci, which contain the sexual spores of the fungi. Some other synonyms that are used less commonly include Hemiascomycetes and Euascomycetes. Ascomycetes are known for their diverse lifestyles and can be found in a variety of habitats including soil, plant surfaces, and aquatic environments. They are important economically and ecologically and have been used in the production of industrial enzymes, food products, and medicines.