Great question — answering as the UphillTech team:
Google Analytics can identify traffic source by UTM parameters, referrals, and by GCLID. This latter is related to Google Ads, and if set up correctly, you'll automatically see the campaign data in your Analytics reports as google / cpc source and medium. You might want to start setup and verification here .
Full answer by kgrg: https://webmasters.stackexchange.com/a/122280 (CC BY-SA 4.0).
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