Things That Use a Lot of Bandwidth

Streaming video services such as Netflix, YouTube and Hulu all require substantial amount of bandwidth for smooth, high-definition video delivery. While each service offers the ability to downgrade your stream to save on bandwidth, it's very easy to transfer data at enormous bitrates using these services. According to a study by broadband research company Sandvine, Netflix accounts for 32 percent of all bandwidth use in North America during primetime hours, with YouTube accounting for another 17 percent.

One of the biggest bandwidth hogs on a computer is BitTorrent, the peer-to-peer file sharing system. When you download a torrent file, your computer becomes part of a network of nodes that are all sharing the same data. Your client sends out requests to others that have pieces you need and once you have downloaded some of the file, your client shares it with others. By default, BitTorrent clients will try to upload and download at the fastest rate possible, dominating your upstream and downstream bandwidth simultaneously. Transferring movies, music or other copyrighted material over BitTorrent can also leave you open to legal action from the intellectual property owners.

Cloud services offer you the advantage of accessing your data using multiple devices and you can connect to the Internet from anywhere, but these services can also require significant bandwidth -- especially if not properly configured. Some cloud storage services allow you to back up folders on your computer to remote servers automatically, treating the online storage as if it were simply another folder on your hard drive. Unfortunately, virus scanners can misinterpret this folder structure, downloading these files repeatedly to scan them during your PC’s regular virus scan schedule and resulting in your client transferring large amounts of data by sending the same files back and forth multiple times.

A sudden spike in bandwidth usage can also be the fault of a malware infection. Many types of malware attempt to disable your system’s security features to allow the author of the program to take control of your computer, turning it into a "zombie." Once a hacker compromises a system, he can use it to launch attacks on other computers, store and transfer files or even take over your email client and use it to send out thousands or hundreds of thousands of spam messages or phishing attempts. Hackers can even collect armies of zombie computers and direct them in large-scale Internet attacks that can overwhelm targets by sheer force of numbers. In most cases, these programs keep data transfer rates low in an attempt to avoid tipping you off, but the bandwidth usage can add up over time.