Multithreading in Java is a feature that allows concurrent execution of two or more parts of a program for maximum utilization of CPU. Each part of such a program is called a thread, and they are lightweight sub-processes. There are two ways to create a thread in Java: 1. By extending the Thread class 2. By implementing the Runnable interface **Using the Thread class:** First, create a new class that extends the Thread class, then override the run() method with the code you want to execute in your thread. Finally, create an object of your new class and call start() on it. ```java class MyThread extends Thread { public void run() { // Your code here } } public class Test { public static void main(String[] args) { MyThread t1 = new MyThread(); t1.start(); } } ``` **Using the Runnable interface:** First, create a new class that implements the Runnable interface and override the run() method. Your thread's code goes inside this method. Then, create an object of your new class and pass it to a Thread object via its constructor and finally, call start(). ```java class MyRunnable implements Runnable { public void run() { // Your Code here } } public class Test { public static void main(String[] args) { MyRunnable r = new MyRunnable(); Thread t2 = new Thread(r); t2.start(); } } ``` Remember, when a new thread is created, the thread is in a new state. When you call start(), the thread transitions to the runnable state. When the thread's run() method execution completes, it transitions to the dead state. This is basically the lifecycle of a thread. Finally, note that you can't control the precise timing of when each thread runs since it is dependent on the operating system's thread scheduler. Multithreading is beneficial in terms of responsive user interface, better use of system resources, and simultaneous and parallel processing. However, it can also lead to issues like deadlock, race conditions, and thread interference if not handled carefully.