A row of three or four numbers — "10,000+ users," "99.9% uptime" — that back up a claim with evidence instead of adjectives. A specific number reads faster and more convincingly than "trusted by many."
Convention is to animate each number from 0 up to its target with a `count-up` the moment it scrolls into view — it holds attention better than a static number and feels like a live tally being counted right now. Keep the unit (+, %, ×) smaller than the number itself, with a label underneath explaining what's being counted.
Inflating a number (calling free-trial installs "1M downloads") or showing a big number with no source erodes trust the moment a user notices the gap. Where you can, add a small footnote or an as-of date next to the figure.
When to use
Only when there's a number actually worth bragging about. If the numbers are small or nonexistent, don't force it — use a different form of social proof like `testimonial-wall` instead.