You can link to other pages to be displayed in the browser or you can link to any file. If the type of file you link to cannot be opened in the browser the browser will ask you to download it. You can also link to specific places on the same page. To do this is simple. That is what tells the browser you are linking to a place on the same page instead of a different file.
Images are very usefull in webpages.
They are an important piece of any web page. They can decide the look and style of your page. In some cases, in most it doesn't really matter, but they say it is good practice to include width and height. Also if one of the image files are missing the pages alignment might get out of whack if you don't put width and height. It will also display that message while the picture is loading.