Ascomycetes are a group of fungi known for producing spores in a specialized sac-like structure called an ascus. This diverse class includes yeasts, molds, and more complex fungi, playing essential roles in ecosystems as decomposers and symbionts. They can be found in various habitats, from soil to decaying wood. Many Ascomycetes are important in food production and biotechnology. For example, Saccharomyces cerevisiae, a type of yeast, is widely used in baking and brewing. Additionally, some Ascomycetes are known for their medicinal properties, such as the production of antibiotics like penicillin.