Dirt is unclean matter, especially when in contact with a person's clothes, skin or possessions when they are said to become dirty. Common types of dirt include:
• Dust: a general powder of organic or mineral matter
• Filth: foul matter such as excrement
• Grime: a black, ingrained dust such as soot
• Soil: the mix of clay, sand, and humus which lies on top of bedrock