Another advertising scheme accesses cookies stored on individual's browsers to determine the types of web sites that have been accessed.

Cookies are small pieces of information that can later be read back from a browser.

When a web site is accessed, a cookie is sent by the web site identifying itself to the web browser.

Cookies are stored by the browser and may be read back by any server that desires to access the cookies at a later date.

Based on the information retrieved from the cookies, a local advertisement targeted to the specific user's interests (based on the web sites that user has accessed or retrieved a cookie from) is provided.

Alternatively, the advertising scheme may evaluate the HTTP referring page information.

To prevent this information from being distributed or used in any manner, software is available that enables users to strip off cookies or HTTP referring page information.

Further, the information collected only pertains to the small set of sites which the advertiser has a business relationship, either directly or indirectly through an advertisement network.

Another advertising scheme attempts to guess the geographic location of a user based on the client's internet protocol (IP) address.

When accessing the internet, individual clients are differentiated from each other by a unique number referred to as an IP address.

In this advertising scheme, a database is maintained by the web host that contains a mapping that provides a correspondence between each IP address to a modem phone number.

The mappings are created by retrieving the modem phone numbers and the different IP addresses that the modem phone numbers correspond to from internet service providers (ISP) (ISPs are companies that provide internet access to users).

By searching the database for the IP address, the web host or advertising company can deduce which modem phone number the user called in from.

Based on the modem phone number and area code, the web host or advertising company can deduce where geographically the user is from or what telephone exchange the user is closest to.

Consequently, the user is provided advertisements based on the estimated geographic location of the user.

Each of the above advertising schemes relies on the insertion and transmission of the advertisement by the web host.

Additionally, each advertising scheme relies on information retrieved from the user (which may be modified by the user) or attempts to guess information about the user.

Consequently, advertising is not precisely targeted and the premiums paid for "good demographics" and "precise targeting" are lower.

The above advertising schemes also create additional processing overhead for the web host (for implementing an advertising scheme), require extra bandwidth to transmit the advertisement across the network to the user, and poorly target specific audiences.

Further, due to the increased overhead and low hit count for small web sites, advertisers are reluctant to advertise on the smaller web sites.