Could you leave out the alt="" tag? What does it stand for when it's not specified? That the image will have original alt?

Answer 1

Nothing will be displayed when a user put the mouse over. This is not necessary but it can work as tags for search engines

Answer 2

Alt is the alternative text or placeholder wich is displayed if there is an error loading the image.

Answer 3

Also, Robin's answer is correct

Answer 4

Yours too :)

Answer 5

Each browser will display a different error, even simply displaying nothing.
Do you remember on IE7 the red "x" at the left top corner? :)

Answer 6

It's not compulsory but it's necessary coz if the browser used to open the page doesn't support the image there is an alternative to bring forth the information