Organism characteristics refer to the traits that define living things. These traits include the ability to grow, reproduce, respond to stimuli, and maintain homeostasis. Organisms can be classified into different categories, such as plants, animals, and microorganisms, based on their unique features and functions. Additionally, organisms are made up of cells, which are the basic units of life. They can be unicellular, like bacteria, or multicellular, like humans and trees. Each organism has a specific genetic makeup that influences its characteristics, allowing for diversity within species and adaptation to various environments.