In JavaScript, there are multiple ways to define an object. Here are the most common ways: 1. Object Literal: The simplest way to create an object is using the object literal syntax, denoted by curly braces `{}`. Properties and their values can be defined within the braces using the key-value pair format. 


   const person = {
     name: 'John',
     age: 25,
     address: '123 Main St',
   };
2. Constructor Function: You can define an object using a constructor function, which serves as a template for creating objects. Inside the constructor function, properties can be defined using the `this` keyword. 

   function Person(name, age, address) {
     this.name = name;
     this.age = age;
     this.address = address;
   }

   const person = new Person('John', 25, '123 Main St');
3. Object.create(): The `Object.create()` method allows you to create a new object with a specified prototype object. You can define properties on the prototype object, which will be inherited by the created object. 

   const personPrototype = {
     greet: function () {
       console.log('Hello!');
     },
   };

   const person = Object.create(personPrototype);
   person.name = 'John';
   person.age = 25;
4. Class: Introduced in ECMAScript 2015 (ES6), JavaScript supports class syntax for creating objects. Classes are essentially constructor functions with a more concise and structured syntax. 

   class Person {
     constructor(name, age, address) {
       this.name = name;
       this.age = age;
       this.address = address;
     }
   }

   const person = new Person('John', 25, '123 Main St');
These are the main ways to define objects in JavaScript. Each method has its own use cases and advantages, so choose the one that best fits your needs and coding style.