Online experimentation allows companies to test hypotheses through controlled studies. At Opentable, they launch 140-200 A/B tests per month to measure the impact of ideas using key metrics like hashtags. Notable wins from social proof experiments included showing top dish tags and restaurant photos on profiles. Urgency experiments found text like "Hurry!" improved conversions. However, adding more timeslots or images higher on pages led to losses. The presentation provided examples of successful and unsuccessful experiments at Opentable.