Short for download and upload. If someone asks how long did the page take to load? He/She is referring to the time it takes a page to appear on your screen. If a web page is loading slow it means that it's taking a long time to fully appear on your screen. You can often scroll through a page and look at the parts that have loaded while the rest of the page continues to load. Also, you can usually click a link on the page you are loading and link to another page without waiting for the current page to fully load.