The classic funnel has four stages: awareness (you exist), consideration (you might fit), decision (you are the right choice), and retention (you keep delivering value). Each stage has different metrics — awareness is measured in reach and impressions, decision is measured in conversion rate and trial activation, retention is measured in repeat purchase and churn.
The 'funnel' metaphor is a useful simplification but increasingly inaccurate. Real journeys loop, branch, and pause. The same buyer might first encounter a brand through social, leave for a year, come back via search, sit on a free trial for six weeks, then buy after a webinar. A linear funnel cannot model this; a journey map can.
What stays true is the principle of stage-appropriate metrics. Top-of-funnel content should be judged on reach and engagement; mid-funnel on lead capture; bottom-of-funnel on conversion. Measuring top-of-funnel content by its bottom-of-funnel conversion is the most common reason awareness budgets get cut.