Exit rate is the percentage of all sessions that include a specific page in which that page was the last one viewed, calculated as exits from that page divided by total pageviews of that page.
Unlike bounce rate, exit rate counts every session that ends on a page, including sessions that involved several pages beforehand — a checkout confirmation page, for example, would naturally have a very high exit rate, since it's the expected final step of a successful visit, not a sign of a problem. This is why exit rate needs to be interpreted per-page and in context: high on an end-of-journey page is fine, high mid-funnel is usually worth investigating.
If a pricing page is viewed 2,000 times across all sessions and is the last page viewed in 800 of those sessions, its exit rate is 40%, regardless of whether those pageviews came from single-page sessions or longer, multi-page visits.
Bounce rate only counts sessions where a page was the sole page viewed in the entire session; exit rate counts every session where a page was the last one viewed, even if several other pages were viewed before it.
No — pages representing a natural end to a visit, like an order confirmation page, are supposed to have high exit rates; it becomes a concern mainly on pages positioned mid-journey, like a cart or pricing page.
Yes, theoretically — if every session that included that page ended there, its exit rate would be 100%, which is expected behavior for something like a logout confirmation page.