What is Affiliate Network
An affiliate network acts as an intermediary between publishers (affiliates) and merchant affiliate programs. It allows website publishers to more easily find and participate in affiliate programs which are suitable for their website (and thus generate income from those programs), and allows websites offering affiliate programs (typically online merchants) to reach a larger audience by promoting their affiliate programs to all of the publishers participating in the affiliate network.
Traditional affiliate networks enable merchants to offer publishers a share of any revenue that is generated by the merchant from visitors to the publisher's site, or a fee for each visitor on the publisher's site that completes a specific action (making a purchase, registering for a newsletter, etc.). The majority of merchant programs have a revenue share model, as opposed to a fee-per-action model.
For merchants, affiliate network services and benefits may include tracking technology, reporting tools, payment processing, and access to a large base of publishers. For affiliates, services and benefits can include simplifying the process of registering for one or more merchant affiliate programs, reporting tools, and payment aggregation.
Affiliates are generally able to join affiliate networks for free, whereas there is generally a fee for merchants to participate. Traditional affiliate networks might charge an initial setup fee and/or a recurring membership fee. It is also common for affiliate networks to charge merchants a percentage of the commissions paid to affiliates.

Network
In addition to the traditional networks, lead generation and CPA networks also exist. Lead generation networks are typically networks that, in addition to performance based promotions (affiliate marketing) also offer CPM- or CPC-based display advertising. CPA networks, on the other hand, are often so-called "super affiliates" who are themselves affiliates of merchants via the traditional affiliate networks, and recruit other affiliates to promote the merchant through them instead of directly via the merchants program at the traditional network.
CPA networks take advantage of the ability to get higher commission rates due to their high volume, which they pass in part down to their affiliates. Average affiliates usually get paid a lower commission if they promote the merchant directly, because they are rarely able to generate the required volume to reach the higher payout tiers.

How Lead Generation Works
The nature of lead generation depends entirely on the decision process of the buyer.
For complex products and services requiring a complex decision process, the keys are identifying the most likely prospects and then educating and qualifying them before deploying more expensive sales resources. The education benefits the buyer; qualification benefits the seller. This gradual lead cultivation process can go on for months and involve several individuals involved in evaluating a solution.
For commodity products, the rendezvous dilemma is one where two parties are seeking each other, but are obscured by time, distance, or attention. In essence there is a set of well-matched candidates for product purchase within a larger set of poorly matched candidates. Those well-matched candidates are what one is seeking to attract or identify in effective lead generation.
Although there are several methodologies and implementations, each involves one of two primary rendezvous strategies: Broadcast or Concentration.
Broadcast involves communicating to a broad set of candidates with the expectation of a statistical response back to the marketer. Advertising is a classic example of broadcast marketing rendezvous.
Concentration involves identifying and creating situations that concentrate well-matched candidates into a broadcast-effective set. Market segmentation and trade shows are classic examples of concentration-marketing rendezvous strategies.