A digital agency's portfolio showcases their strengths and experience in digital marketing, including web design, social media management, SEO, PPC, and content marketing. Look for projects relevant to your industry to gauge their ability to meet your needs. Pay attention to aesthetics, user-friendliness, and results achieved for clients. Testimonials and case studies provide insight into customer service, communication, and timeliness. A portfolio should inspire confidence in the agency's ability to meet your digital marketing needs.