A/B testing is a valuable tool for marketers that can provide insights into customer behaviour. By creating two different versions of a marketing asset and sending them to a large pool of customers, marketers can see which version performs better. This allows them to fine-tune their marketing efforts and improve the overall effectiveness of their campaigns. A/B testing can be used to test any element of a marketing campaign, from the headline to the call-to-action, and its use can make a significant difference in the success of a marketing campaign.