Also called a marketing, or sales funnel.
An analogy used to depict the journey your users take as they move through your website, acquiring your company’s products, or services.
The image of a funnel aptly represents how traffic dwindles as visitors move through each stage of your website. Compared to those who initially landed on your site, only a small percentage may make it to the final stage.
Those who do make it through the final stage -- whether it be completing a purchase or signing up for a newsletter, for example -- have completed the conversion; they've made it all the way through the funnel.