Content credibility is affected by a variety of factors, with source credibility, content quality, content design, and content tone being among the most important ones. To bolster source credibility, you can include author bios, testimonials, reviews, awards, logos, and endorsements. Content quality can be improved by conducting thorough research, citing credible sources, updating outdated content, and responding to your audience's questions and concerns. Content design should be optimized by using clear headings, subheadings, lists, images, videos, charts, and other visuals that make your content easier to scan and understand. Finally, you should adjust your content tone to suit your audience, purpose, and context; for instance, you may use a formal tone for academic or technical content, a casual tone for blog posts or social media posts, and a persuasive tone for sales or marketing content.