Streaming is a technology that allows a continuous flow of information into your computer. A few years ago, files delivered to your browser from World Wide Web servers (HTML documents, image files, video files, etc.) had to be downloaded in full before the browser could start displaying them or a plug-in could play them. Streaming technologies changed that.

Streaming will let you listen to music over the Internet without having to wait for the complete music file to reach your system. The technology has been optimized for what is called real-time delivery. After only five or ten percent of the file has reached your computer, the plug-in can begin playing it and you can enjoy it while your browser continues to download the rest of the file.

Streaming is used by many plug-ins, such as RealPlayer, as well as by standalone products like PointCast Canada.

It may seem strange that so much Internet-related software is given away free to the public. Why is this? Is the software still in the experimental stage? Was it created for fun by non-profit hobbyists? Does it do so little that they don't think people will pay for it?

Originally, yes. Traditionally, much of the shareware and freeware available on the Internet was amateur work. The programs have often had small bugs in them or amateurish interfaces. And they have frequently been designed to do small and specific chores by playful, anti-capitalist hackers. With the popularity of the World Wide Wide, however, much of today's free software is part of a determined corporate struggle for control of the new market. There are a variety of business reasons why most plug-ins come free today.

By giving you the plug-in for free, the company gets you hooked on the product so you'll pay for it later. This is the whole idea behind shareware, and also the philosophy that explains demo versions of big-name software.

Another reason has to do with the fact that plug-ins are nothing without content on the Web for them to display. Most of the plug-in makers also produce content development tools which are not free. For instance, the Shockwave plug-in is free, but Macromedia's Director program suite, which is used to create Shockwave material, is not. There are also some plug-ins that won't work well or at all without the addition of server software on the Web site. For example, the RealAudio plug-in is free, but for true audio streaming a Web site has to be running the RealAudio server, which must be purchased. By popularizing free plug-ins, the plug-in makers can sell the software needed to make the content.

It's hard to say. As The Future of browser plug-ins explains, support for audio, video, 3D effects, and VRML will most likely be a part of all standard browser packages in the future, and applications that handle things like spreadsheets and word processor documents will probably be capable of accessing the Web themselves, without an intermediary browser. What is a free plug-in today could thus become a feature of an application in the future, whose cost would be worked into that of the overall product. The plug-ins that already exist, however, stand a good chance of remaining available for downloading for the foreseeable future.

It depends on the plug-in. The average size of a plug-in installation package is probably around 1 megabyte (1 MB), which should take less than ten minutes to download with a 28.8 kbps modem connection. However, some plug-ins, such as Shockwave and Acrobat, are between 2 and 5 MB. During busy times (such as evenings), and with slow or popular download sites, the download time for a large plug-in can be longer. See our Help pages for instructions on downloading. Do they take up a lot of disk space?

Adding a plug-in to your browser will typically use up between 1 and 3 MB of hard disk space. However, it depends on the plug-in. If space on your hard drive is an issue, you can save space by deleting the original installation files you downloaded from the Web.

You need at least a 28.8 kbps modem connection to get the most out of the average plug-in. RealPlayer has a plug-in optimized for 14.4, and many plug-in manufacturers claim that their products work at 14.4, but the truth is that the wait for plug-in content is often frustrating at that speed, and sometimes even at 28.8. Streaming media such as audio and video can also be unsatisfying over modem connections, and the slower the connection the more likely the signal is to be rough. In general, the faster your connection, the more you'll enjoy using plug-ins. A fast processor (the speed of your computer, in megahertz) with lots of RAM will also improve your enjoyment of plug-in material.

If the browser doesn't find the plug-in it will usually let you browse for it on your hard drive, so it's a good idea to keep track of where the installation program put it. Often exiting your browser and starting it again, or restarting your computer will solve the problem. Depending on the size of the plug-in content, the time of day, the robustness of the site, and the speed of your connection, it can take 5 to 15 minutes, or longer, for the plug-in to start playing the content. The more RAM your system has the more likely it is that the content will be played smoothly once it has been downloaded.

You may be told that your browser has performed an illegal action, or in Windows 3.1 you may get a "General Protection Fault." In the worst case, a plug-in could crash your computer, making it unusable until you reboot, and causing you to lose any data you were working on in other open programs.

Proceed with caution after you install a plug-in. Close any programs except for your browser and test a few different sites with the kind of content your new plug-in was designed for. If all seems to go well, you can probably relax and go back to browsing the Web in your usual manner, but if the plug-in consistently causes problems you may decide to uninstall it or just avoid content that was designed for that plug-in.

Some people have wondered whether they can feel secure using plug-ins. They worry that plug-ins may pose a greater threat to security and privacy than a browser on its own does. A plug-in designed by a malicious person could conceivably erase your hard drive or send information about you and your computer over the Internet. However, that is true of any software. Plug-ins made by the companies we have profiled here have a reputation for being virtually risk-free from that point of view.

As always, it depends on the plug-in. Except in the case of the most popular plug-ins, a lot of the material created for plug-ins has been created just to show that it can be done, and the audience for any given plug-in is limited. If you think it would be fun to listen to Seattle's classical music station over the Internet, if you'd like to watch a really short clip from a new video, then plug-ins - or at least a careful selection of them - are probably for you. On the other hand, if you're the kind of person who turns off images in your browser because you don't want to wait all that time just to get to the solid information you're after, plug-ins may seem to be a waste of time and bandwidth to you.