This tag is called as line break. It tells the browser when a line has ended and to start on the next line. Key in the code below on your favorite text editor to see the effect of <br> tag in action.
<html> <head> <title>Line Break Tag</title> </head> <body> I am the first line.<br /> I am the second line.<br /> I am the third line.<br /> I am the fourth line. </body> </html>
The code above produces this page in Mozilla Firefox: