As the Internet's most visible feature, the web attracts hundreds of millions of visitors every day. Wherever you get a large crowd of people together, there are bound to be some shady characters looking to make a quick buck or just cause trouble, and the web is no exception. Unfortunately, the interconnected nature of the web makes it tricky to avoid danger altogether.
In order to browse the web safely and securely, one must consider and take measures to address (through software, behavior, or both) a number of issues.
Picture the simplest possible web activity: visiting a single web page. Merely by typing a URL in your browser, you set in motion a series of actions that can reveal private information to other people. For example, any or all of the following could (and often do) happen:
The web server you visit records the time and date of your visit, which page you viewed, details about which browser and operating system you used, the resolution of your display and how many colors it supports, your browser's default language, the last page you visited, and your IP address — which can in turn reveal your ISP and your geographical location, sometimes right down to your street address. The server may also calculate your connection speed and, if you visit more than one page, track how much time you spend on each one. Some servers collect even more information.
The web server may write information to a file on your disk called ...