Buying revenue is not the same as earning it. Organic growth is the measure that separates the two, and it is the number a management team is genuinely accountable for. Companies disclose a bridge from reported to organic growth in the release.
Definitions vary in how long an acquisition stays excluded, usually twelve months. Watch for a company that quietly shortens the exclusion window in a year when acquisitions were large.
Example: Northwind Tools reports 8.0% growth. The September distributor acquisition contributed 2.6 points and currency cost 0.4 points, so organic constant-currency growth was 5.8%.
Related: year-over-year, constant-currency, pro-forma, revenue, segment-reporting