Conversion

A conversion happens when a visitor completes a specific action you've defined as valuable, such as buying a product, filling out a form, or signing up for a newsletter. The conversion rate is the percentage of visitors who complete the conversion.

What counts as a conversion is up to you, and it doesn't have to involve money. For a nonprofit it might be a volunteer signup; for a B2B site, a downloaded white paper. Conversions usually sit at the end of a conversion funnel and make good KPIs, because they measure something you wanted to happen.