Which of the following is NOT a digital marketing method?

Billboards represent traditional marketing rather than digital marketing methods. They are physical advertisements placed in high-traffic areas to capture the attention of potential customers, utilizing print media to convey messages about a product or service. In contrast, the other options—email marketing, social media marketing, and pay-per-click (PPC) advertising—are all conducted through digital channels. Email allows for direct communication with potential clients, social media facilitates engagement and brand awareness across platforms, and PPC involves paid online ads that appear on search engines and other websites, driving traffic through targeted online campaigns. Thus, billboards stand apart as a non-digital approach in the realm of marketing strategies.