Components add functionality to a GameObjectThe fundamental object in Unity scenes, which can represent characters, props, scenery, cameras, waypoints, and more. A GameObject’s functionality is defined by the Components attached to it. More info
See in Glossary. To customize and add to the components in the Editor, you can write your own scriptsA piece of code that allows you to create your own Components, trigger game events, modify Component properties over time and respond to user input in any way you like. More info
See in Glossary.
To create a component with script, you need to write the script and then attach it to a GameObject. Scripts attached to a GameObject appear in the GameObject’s InspectorA Unity window that displays information about the currently selected GameObject, asset or project settings, allowing you to inspect and edit the values. More info
See in Glossary window because the Editor treats them as built-in components.
For information on how to create a script, see Creating and Using Scripts.