Copy and paste the following HTML code in a file (e.g. Notepad) and save as "first.html" .
After saving the file, double click the "first.html" file.
Then you will get a Message box with the message "Hello, world!!" .
An alert box is often used if you want to make sure information comes through to the user. Here, the alert() method displays an alert box with a specified 'Hello, world!!' message and an OK button.