In digital marketing, BoFu means “Bottom of Funnel” and refers to content that drives conversions (such as an optimised sales page), as well as content that helps retain existing customers (such as help pages).
The funnel in question is the marketing funnel and is the journey people take from becoming aware of your website to undertaking an action (such as making a purchase).
BoFu, or Bottom of Funnel in this sense means the point just before someone undertakes the action you hope they will. This could be a sales or sign up page for example or even just a page with a prominently placed phone number on it.
Optimising these pages is often seen as the most important thing in order to improve conversion rate, however, without preparing the way with ToFu and MoFu content, even a good BoFu page can often fall flat.