When I made (alt="") removed, the result is the same

Answer 1

"alt" is the alternative text used in <img> (not only) witch takes the place of the image when it can't be loaded.

Answer 2

you will notice the text of alt="my image" when you give an invalid or unreachable image link

Answer 3

When image takes time to load or its not being loaded at that time the text which is written in "alt" is displayed !!