Most already include algorithms that learn from prior queries in order to return more useful information. Most popular shopping bots are resident on the web, but some are programs that are downloaded by the user and are resident on the local hard drive. The downloaded programs operate in a similar manner to the web-based interfaces, but with a different revenue model. Web-based shopping bots generate revenues through a combination of advertising and commissions on sales linked through the shopping bot. User resident programs generally can be downloaded as a shareware version with reduced functionality, or purchased as full-function software.
Some bots are available in both forms.
Vendor-shopping guides these bots tend to be the easiest to use, but are limited to the vendors they link to. Most rely on the vendor to supply the pricing information in a format they can understand. The independence of these services is often doubtful, and preferred vendors will often receive the top spots in the search result list. Most of these bots specialize in books, music, videos, or computer equipment. They tend to be very comprehensive and easy to use, capturing the majority of web-vendors with a single query.