Soft tissue refers to all the body's supportive tissues that aren't bone or teeth, including muscles, tendons, ligaments, fat, blood vessels, nerves, and fibrous tissues, which connect, support, and surround organs and structures, allowing movement, cushioning, and providing support. Injuries often involve strains, sprains, or tears from trauma or overuse, leading to inflammation, pain, and swelling, while conditions like tumors (soft tissue sarcoma) can also affect these areas.