The core principle of affiliate marketing is that the referring affiliate earns a commission if a referred prospect makes a purchase. Any affiliate program that aims to succeed in its recruitment efforts must uphold this principle, regardless of whether the prospect buys immediately, or delays her purchase until some time in the future.

To fairly and accurately distribute affiliate commissions requires a database that maintains a list of the relationships between prospects and the affiliates that referred them. Ideally, this database would be centralized, hosted as part of the software application that manages the affiliate program. But this approach would only be feasible if web visitors could be automatically distinguished from each other, using a unique and permanent identity code.

Unfortunately (for affiliate program operators) web users prefer to surf anonymously. Web browser software is designed to allow a surfer to visit any website without leaving a personal identity trail. So, affiliate programs need a less intrusive method of tracking the associations between their members and the surfing public. The solution adopted by most programs, including ClickBank, is to distribute the database throughout the internet, storing a tiny fragment of information on each prospect's computer. They implement this using cookies.

ClickBank uses a mechanism known as the hoplink system to record cookies on a prospect's computer, storing multiple affiliate referral relationships in a single cookie. Every time a prospect is referred to a new merchant, her existing referral cookie is updated to reflect the association between the new merchant and the affiliate that referred her.

The hoplink system is invoked automatically whenever a prospect is referred to a ClickBank merchant by an affiliate. When a prospect clicks on a referral link, she is initially directed to ClickBank's hoplink server. The server, in turn, sends her the referral cookie and immediately redirects her to the merchant's website. The destination of the redirection is known as the merchant's landing page and is configured within his ClickBank account settings. A landing page is a merchant web page designated to accept inbound affiliate referrals.

The hoplink system is implemented by two architectures that operate in parallel. The original architecture, known as the regular hoplink system, has been in operation since the launch of ClickBank, but it has come under criticism for its inflexibility and the ease with which it allows commission theft. Announced in October 2003, the enhanced hoplink system aims to overcome the security shortcomings of the original system and to provide support for a range of new features that will improve the effectiveness of the affiliate system.

Aside from improvements in security, the enhanced hoplink system is designed to capture additional data that will enable detailed reporting of affiliate referral statistics and merchant conversion rates. Perhaps most significant of all, it provides support for referral links to multiple landing pages at the merchant's website - an essential feature that has previously been noticeable by its absence.

Affiliates with established businesses that use regular hoplinks are free to continue without modifying their existing configurations. But to exploit the richer functionality resulting from ClickBank's ongoing system development, it is worth upgrading to the enhanced hoplink format.