Some analysts believe that eventually e-commerce will account for one-fifth of all retail sales. The numbers for business-to-business e-commerce are even higher. That will likely apply to buying and selling political campaign products and services as well.

Even if you haven't experienced it, you've undoubtedly read about it. Shopping on the Internet, whether as a consumer or as a business, is exploding in popularity.

Various studies indicate that from one-quarter to one-half of all Americans have now placed at least one order online. Some analysts believe that eventually e-commerce will account for one-fifth of all retail sales (the figure today is between 1 and 5 percent, depending on who's doing the counting). The numbers for business-to-business e-commerce are even higher.

This trend has important implications for political campaigners, who can buy a lot of things on the Internet, from bumper stickers to yard signs, office supplies to voter lists, compliance software to airline tickets. The Web gives campaigners a chance to find vendors who can meet tough time deadlines as well as budget limitations.

There's no better way to locate hard-to-find items or comparison-shop for the best deals. I've shopped for cars and plane tickets on the Web, and recently I bought boogie boards for my kids, videos for my wife, and specialty bath mats and pillow wedges for the house -- all items I couldn't find in local stores -- at excellent prices.

E-commerce has had a society wide impact, helping to fuel the economy's decade-long expansion, the longest since records were first kept 150 years ago. But to almost every upside there's a downside. With e-commerce, you need to beware of scams and foul-ups as businesses and entrepreneurs eager to cash in on the Internet gold rush do so ill-prepared or with venal motives.

The incidence of outright fraud appears to be low, with exceptions in the areas of pyramid schemes and, to a lesser extent, online auctions. More common problems are featured products being unavailable, late deliveries, high shipping charges and orders never arriving.

The key issue is trust. If you're buying, how can you trust Web merchants? If you're selling, how can you engender trust in prospects? As often happens with Web problems, the Web offers solutions as well.

Web sites can engender trust by being forthright and by understanding Internet conventions. If you have a storefront, post its address along with a telephone number for those who want more than a virtual connection or assurance that you're no fly-by-night operation. Make sure your site loads quickly, is easy to navigate and has a search feature. Don't send e-mail to Web visitors without asking permission.

Unfortunately, Web safeguards aren't fool-proof. A new, fraudulent Web site may have not yet registered on the radar screens of consumer watchdog sites. Shopping review sites seem eager to give sites good marks and reluctant to reveal poorly performing sites. Shopping discussion sites by definition report anecdotal information that may be useful, or misleading.