JavaScript objects are a powerful way to organize and manipulate data in your code. To declare an object, use curly braces {} and define key-value pairs inside. Access or modify a property using dot notation (e.g., objectName.propertyName) or bracket notation (e.g., objectName['propertyName']). To add new properties or update existing ones, simply assign a value to the property. You can also delete a property using the delete keyword. Objects can contain not only data but also methods, which are functions defined as object properties. To call a method, use the objectName.methodName() syntax. Overall, JavaScript objects provide a flexible and versatile way to structure and work with data in your applications.