What does that.... alt="" ...do in the code

Answer 1

If your image doesn't displays , anything written in alt tag inside double quotes will be displayed instead of image

Answer 2

In case due to some problem the system is unable to show the image
It will show an alternative text in place of the image.... It's actually not very important....

Answer 3

alt attribute is useful if the user internet disconnects or weakens or even their is a mistake in src value for any reason, any thing you typed insie alt it will be displayed instead of image...