An applet is a Java program designed to run in a web browser, extending the java.applet.Applet class without utilizing a main() method. Applets require a Java Virtual Machine (JVM) and follow strict security guidelines known as sandbox protection. The applet lifecycle includes methods like init, start, stop, destroy, and paint, which manage initialization, execution, and resource handling.

1. Java Applet Basics
An applet is a Java program that operates in a Web browser. An applet can be a completely
efficient Java program because it has the entire Java API at its convenience.
There are some important variations between an applet and a individual Java program, such as the
following:
An applet is a Java class that expands the java.applet.Applet class.
A main() technique is not invoked on an applet, and an applet class will not determine main().
Applets are designed to be included within an HTML web page.
When a customer opinions an HTML web page that contains an applet, the program code for the
applet is downloadable to the customer’s device.
A JVM is required to view an applet. The JVM can be either a plug-in of the Web browser or an
individual playback atmosphere.
The JVM on the customer’s device makes an example of the applet class and makes various
techniques during the applet’s life-time.
Applets have tight protection guidelines that are required by the Web web browser. The protection
of an applet is often known as as sand box protection, evaluating the applet to a child playing in a
sand box with various guidelines that must be followed.
Other sessions that the applet needs obtainable in a single Java Database (JAR) computer file.
Life Pattern of an Applet:
Four techniques in the Applet class give you the structure on which you develop any serious applet:
init: This approach is designed for whatever initialization is needed for your applet. Stage system
after the param labels inside the applet tag have been prepared.
start: This approach is instantly known as after the web browser phone calls the init technique. It is
generally known as whenever the customer profits to the web page containing the applet after
having gone off to other webpages.

2. stop: This approach is instantly known as when the customer goes off the web page on which the
applet rests. It can, therefore, be known as continuously in the same applet.
destroy: This approach is only known as when the web browser turns down normally. Because
applets are made to live on an HTML web page, you should not normally keep sources behind after
a customer results in the web page that contains the applet.
paint: Invoked instantly after the start() technique, and also any time the applet needs to paint itself
in the web browser. The paint() technique is actually got from the java.awt.
The Applet CLASS:
Every applet is extra time of the Java.applet.Applet class. The bottom Applet class provides
techniques that a produced Applet category may call to obtain details and services from the web
browser perspective. You can learn Java programming very easily.
These include techniques that do the following:
Get applet parameters
Get the system place of the HTML computer file that contains the applet
Get the system place of the applet category directory
Create a position concept in the browser
Bring an image
Bring a sound clip
Play a sound clip
Re-size the applet
Additionally, the Applet class provides an interface by which the audience or web browser acquires
details about the applet and manages the applet’s performance. The audience may:
demand details about the writer, edition and trademark of the applet
demand an explanation of the factors the applet recognizes

3. initialize the applet
eliminate the applet
start the applet’s execution
stop the applet’s execution
The Applet class provides standard implementations of each of these techniques. Those
implementations may be overridden as necessary. You can learn java by joining the java class or
you can also go through the java tutorial java for beginners.