The term refers to the categorization of laundry loads based on the type and level of soiling. This involves assessing factors like the visibility of dirt, the presence of stains (e.g., oily, protein-based), and the embeddedness of grime within fabric fibers. A garment caked in mud would be categorized differently than one lightly soiled from everyday wear.
Understanding these categories allows for more effective cleaning. Selecting the appropriate wash cycle based on fabric type and soil level ensures optimal results, preventing damage to clothing while effectively removing dirt and stains. This knowledge developed alongside the evolution of washing machines, progressing from basic agitation to complex programs tailored for various textiles and soiling levels. Efficient cleaning practices minimize water and energy consumption, contributing to resource conservation.