You can access and modify object properties in two ways: dot notation or bracket notation.

Dot Notation

This is the most common way to access or modify properties.

Example:

let car = { brand: "Toyota", model: "Corolla" };
console.log(car.brand);  // Output: Toyota

car.model = "Camry";
console.log(car.model);  // Output: Camry

Bracket Notation

Bracket notation allows access to properties with variable names or property names that include special characters or spaces.

Example:

let person = { "first name": "Manjeet", age: 25 };
console.log(person["first name"]);  // Output: Manjeet