As you know by now, the Internet allows files to be exchanged between computers. When you are just viewing webpages, the contents of the page are only temporarily saved on your computer (just for as long as you are viewing the page). Web browsers can only read certain file types, namely those with the .html extension (HTML files) and certain picture files like .jpg, .gif, and a few others. There are other file types that you might encounter on the Internet that you want to see, though, such as Word files, music files, etc. that the browser cannot open. In order to open them, you need to transfer a copy of the file from the Internet to your computer, and open it with an application on your computer. The process by which files are transfered from the Internet to a computer is called
downloading. Once a file is downloaded, it can be treated just like any other file you created yourself on your computer. Two of the most common sources for downloads are emails and the iTunes music store. Downloading is an amazing process—I can write a novel on my computer and send it (attached to an email) anywhere in the world and the email's recipient could be reading it within seconds. With great power, though, comes great responsibility: while many downloads are regular, harmless files, there are a large number of files that contain viruses and other programs that can harm your computer or steal your information. These files are often disguised as regular files, so it is important to use caution when you click on a link to download a file.
Only click on links that appear on web sites that you trust!!! A good rule of thumb is that if you don't expect to have to download a file,
don't download any files. Also, only download attachments from emails if you know the person who sent the email to you. Many email services have great software that tries to filter out messages that have viruses attached to them, but none of them is perfect, so it's always best to err on the side of caution.
A much less hazardous process than downloading is the reverse: uploading. When you want to share a file with someone (or the whole Internet), you need to upload it to an email or web site so that others can download it to their computers.
Examples
When you buy a song from iTunes, you have to download it in order to play it on your computer.
A file that contains a virus may appear as simple as this (this is not a real virus, or even a real link):
Congratulations! You just won $100!!!!! click here to claim your prize.
Even though you might be flattered at the thought of winning $100, since you did not log on to the Internet today to claim a lottery prize, you are better off not clicking the link.
Most email programs have a button that says "Attach a file" or has a picture of a paper clip on it. Clicking that will let you choose which file you want to attach, and when you send the message, your file will be uploaded to the Internet.
Up Next: Navigating through your computer
