What it means
TOFU (top): people becoming aware of a problem — broad content, reach campaigns, brand. MOFU (middle): people evaluating options — comparisons, lead magnets, retargeting. BOFU (bottom): people ready to buy — demos, branded search, offers.
Why it matters
Most teams over-invest in BOFU because it shows the best ROAS, then wonder why growth plateaus — they are harvesting demand without creating it. A healthy engine funds all three stages, with messaging and metrics matched to each: reach and recall at the top, conversion at the bottom.