Living things are organisms that exhibit characteristics such as growth, reproduction, and response to stimuli. They can be classified into various categories, including plants, animals, fungi, and microorganisms. Each of these groups has unique features that help them survive in their environments. All living things are made up of cells, which are the basic units of life. They require energy to carry out essential functions, often obtained through processes like photosynthesis in plants or respiration in animals. Living organisms interact with each other and their surroundings, forming complex ecosystems.