Dothideomycetes is a large and diverse class of fungi within the phylum Ascomycota, characterized primarily by producing their sexual spores in specialized, often darkly pigmented structures called ascomata, which typically have a flask- or disk-like shape. Members of this class exhibit a wide range of lifestyles, including saprophytes that decompose dead organic matter, plant pathogens causing leaf spots and cankers, and endophytes living harmlessly inside plants. They are ecologically and economically important due to their roles in nutrient cycling, agriculture, and occasionally human health. Morphologically, Dothideomycetes are noted for their bitunicate asci, which have a double wall that helps in spore release, and their spores are often septate and pigmented. Overall, this class represents one of the most diverse groups of filamentous fungi in both habitat and function.