"Sac fungus" refers to a group of fungi that form distinct sacs or ascus structures. There are numerous synonyms for this term, including "Ascomycota," "ascos," "cup fungi," and "sac fungi." Additionally, specific species of sac fungi may be referred to by their scientific names, such as morels (Morchella spp.), yeasts (Saccharomyces spp.), and truffles (Tuber spp.). These fungi play important roles in various ecosystems, serving as decomposers, mycorrhizal partners, and plant pathogens. Additionally, many sac fungi are prized for their culinary and medicinal properties, making them of significant economic and cultural importance.