Coffee takes a series of steps, all of which strongly effect the resulting product:

• The growth and harvesting of coffee beans.
• Roasting.
• Packaging, shipping and storing. (I'm probably missing a few important steps here.)
• The grind. I knew that freshly ground was better than pre-ground, but a new burr grinder proved that the uniformity and granularity of the grind is a much bigger factor than I imagined.
• The quality of the water.
• The heat of the water and the manner in which it interacts with the grounds.
• The filtration of the coffee into a container.
• How soon the coffee pot is rescued from the heating element.
• The coffee cup: how the heat of the coffee is managed (or not), how air mixes with the coffee, the way that that the coffee comes out of the cup when you sip (or chug) it.

A great cup of coffee requires more than picking a good brand and blend at the grocery: Every step is a chance to completely ruin or bring out the true potential of the previous step. I could just as easily be talking about wine, or chocolate, or almost any product (or service!) My choice of coffee probably has something to do with the mug next to me as I write this.

This is also true for website success (which may or may not be more important than a truly good cup of coffee.) A visitor browses through a sequence of pages with a certain goal or general desire in mind (craving a good cup of coffee). They may find what the want, or they may find an alternative (e.g. discovering the earthly delights of a french press brew.) Or they may leave (sorry, we don't serve tea.) Every page they visit effects both the chance of success and the quality of success.

A common e-commerce anology for the purchase process is a funnel. The top of the funnel represents prospects: people who arrive at a website, or look at a product page, i.e. might be interested in buying something. The next step down the funnel might be the user clicking 'more info'. The next step is adding to the shopping cart. Then viewing the shopping cart. Then beginning the checkout process. There's a step in the funnel for each step in the checkout process, ending in a completed transaction. An ideal funnel is a straight cylinder, where all prospects buy something. By identifying the squeeze points (lowest conversion rates) in the funnel you can figure out what part of the process needs to be fixed most.

The funnel can be applied to the rest of website design too, because a purchase is not the only goal. Create funnels for visitor registration, getting to the 'about us' page, e-mailing a page to a friend, or just about any visitor milestone. Figure out how visitors actually use your site by analyzing weblogs and usability studies.