box. In this context, dealt with means you've taken the trouble in the past to manually delete cookies set by the Web site by using the Cookie Manager. Such drastic and specific action probably means the Web site did something untrustworthy in your eyes. This option allows you to automatically block cookies from all such Web sites in the future so you don't need to waste time doing so manually. From the Cookies tab, you can also view, search, and remove stored cookies by clicking the View Cookies button. The Cookie Manager opens to offer information about the cookies on your computer, organized into groups by the Web site who stored them, as shown in Figure 14-6. To find a cookie more quickly, you can enter part of its name or originating site address into the Search text box. To view information about a particular cookie, select it and look at the bottom of the screen. Most of the supplied information is of a highly technical and irrelevant nature, but you can also take a look at when the cookie is set to expire. If you aren't happy with what you see, you can manually remove the cookie by clicking Remove Cookie. You can also remove all stored cookies by clicking Remove All Cookies. Note that both actions take place as soon as you click their respective buttons, and you can't undo a removal. Figure 14-6: The Cookie Manager displays info about every cookie stored on your computer and allows you to remove any that you find suspect. Clearing your cache You want to go to a new restaurant in town, so you call for directions. It's so good that you decide to go there every night. Are you going to call for the directions every night? Probably not. At some point, the head waiter is going to recognize your voice and ask why on earth you keep calling - the restaurant isn't moving! You would, of course, write the directions down or commit them to memory. In the digital world, the idea that you can make copies of information instead of constantly returning to the source is known as caching. Technical details aside, caching allows Firefox to make copies of Web sites you visit frequently and store them on your computer so they load more quickly. When you instruct Firefox to visit a Web site, it simply compares the version stored on your computer with the current version. If they're the same, it saves time by loading the Web site directly off your computer. By default, Firefox caches the last 50MB worth of Web sites that you visit onto your computer. To configure or clear the cache, follow the directions in the section "Working One-on-One with Your Data," earlier in this chapter, to get to the Cache tab of the Options window. From there, you can do any of the following: Increase or reduce the amount of hard drive space Firefox uses to store cached Web sites on your computer by entering a new number in place of 50. Most computers these days have so much hard drive space that 50MB is but a tiny fraction, so you probably shouldn't worry about reducing this number. If you have available hard drive space, enlarging the number improves page-load performance because Firefox can cache more sites. TECHNICAL STUFF A megabyte (MB) is a technical unit of measurement used to describe how much space something uses on a computer. Many computers these days have at least 20 gigabytes (GB) of space, which - because a gigabyte roughly equals 1,000MB - is equivalent to about 20,000MB. Clear the current cache by clicking the Clear Cache Now button. This action takes place as soon as you click the button and is irreversible. Note that this doesn't turn off the cache; it clears only the currently cached sites. New cached Web sites accrue as soon as you begin surfing. If the Clear Cache Now button is unavailable, your cache is already empty.