A "gobo" is a stencil or template placed in front of a light source to create patterns or shapes of light. Commonly used in theater and photography, gobos can project images like trees, clouds, or abstract designs onto surfaces. They are typically made from metal or glass and can be customized for specific effects. Gobos are often used in stage lighting to enhance the visual atmosphere of a performance. By manipulating the light, designers can create mood and depth, making the scene more engaging for the audience. They are also popular in events and parties for decorative lighting effects.