Imagine if someone — or even several people — followed you around all day, every day, with a video recorder. They recorded everything that you did, from when you woke up in the morning to what you had for breakfast to what you just bought at your supermarket to where you worked. Then, they occasionally offered suggestions on things that you might want to buy, or used their mobile phones to call someone else and tell them about everything they've seen.
Every time you use your web browser to go somewhere on the Internet, this is sort of what happens. Websites, corporations, and data collection companies use invisible background programs to track your online activity, from what websites you log into to what terms you type into a search engine to what you buy on shopping websites. They use this information to build a virtual profile of who you are, and then sell this profile to advertisers, companies looking to hire, or even health or insurance providers.
The trade-off is that many of the websites that track you offer you some sort of service for free. Google, for example, offers its search engine, an email client (Gmail), and an online suite of office software (Google Docs) all without you having to pay for them. Is that a fair trade? We'll leave that to you to decide.
How is my Internet activity being tracked?
There are a couple of different ways that companies can track your activity online. These include:
Cookies: These are small files that websites put on your computer as reminders of where you've been and what you've done on the Internet. Some are useful and make using websites easier or possible, but others are intrusive and track your habits. See our What are Cookies article for more information.
IP address: When your computer connects to the Internet, it's given a unique number that distinguishes it from every other computer on the Internet. Websites that you connect to can see this address, and can use parts of it to figure out what country, region, or even city you live in.
User-agent strings: These are lines of computer code that identify what program you're using to connect to the Internet or World Wide Web. Using these, trackers can tell what type of browser you're using (e.g. Chrome, Firefox, Internet Explorer, and so on).
Cache: Your cache contains copies of files on a website that your computer stores. It makes it easier to load web pages by simply loading the stored files (if this is possible) instead of asking for them directly from the web page's server. However, the contents of your cache can reveal where you've been on the Internet, and — if your cache contains multiple versions of the same web page — how long ago you've been there. See our What is a Cache and Internet Browsing History article to learn more.
How can I tell if my Internet activity is being tracked?
Other than that, it's somewhat difficult to tell when you are or aren't being tracked on the Internet. Most tracking activity is done by behind-the-scenes programs that work without your knowledge or explicit consent (i.e. you're agreeing to let them work by simply using a website).
There are some places where you won't be tracked (or at least as heavily tracked), such as when you're logging into accounts or inputting other sensitive information (e.g. when you're doing online banking). However, as a general rule: if in doubt, always assume that you're being tracked on the Internet.
How can I avoid being tracked on the Internet?
Fortunately, as awareness increases regarding the amount of tracking activity that happens on the Internet, certain companies and organizations have begun offering services that help people keep their online activity private. Some options include:
Web browser add-ons: Certain web browsers now have options or extra features (usually free) that tell websites not to put information on your computer that could be used to track you. They don't always work, but they're better than nothing. Some browsers also have add-ons that can fool websites into thinking that you use a different browser, which makes you harder to track.
Private search engines: In response to the tracking practices of the "big three" search engines (Google Search, Yahoo Search, and Bing), some search engines have been created that do not track you. They sometimes piggyback off of larger search engines, but they do not store your IP address or the terms that you search for. There are other websites besides certain search engines that do not track your activity, as well.
For more on private search engines and a list of some of the more popular ones, see our Private Search Engines article.
IP spoofing: There are some programs or websites that can allow you to temporarily modify your computer's IP address. This messes with systems that analyze your IP address to tell where you are in the world, and can make it seem like you're connecting to the Internet from a completely different country. This can really throw Internet trackers off your trail.
See our IP Spoofing article for more on what this practice is, and some ways to do it.
Proxy websites: These websites allow you to browse the Internet by funneling your activity through them. This means that most of what you do on these websites only gets tracked back to the proxy website, and not to you as an individual user.
Private web browsers and Virtual Private Networks (VPNs): These are programs that combine IP spoofing with the functions of proxy websites (and even some browser add-ons) for an all-in-one private Internet experience. They modify your IP address so that trackers don't know where you're connecting to the Internet from, and use a fake server to connect you to websites so that your activity can't be traced back to you as an individual person.
Private web browsers are different from simply using "private mode" in more common web browsers. To find out how, see our Private Web Browsers article.
There! Now you know that these information-tracking practices happen on the Internet, how (to know if) you're being tracked, and what steps you can take to keep your online activity private.