In order to make image u need to type <img src="tree.jpg" alt="" /> For what is the alt=""
Alt specifies the text which will be displayed if the image fails to load for some reason.
If the browser fails to display the image,the text or sign will be shown what was given in the " " quotation marks!! It also makes easy when you search That kind of image!! You can easily find out that image by searching with that keywords!