Success online continues to depend on getting and keeping a high ranking on search engine results pages (SERPs), even in the always changing world of digital marketing. In order to offer a comprehensive grasp of the importance, methods, and optimal practices of Search Engine Optimization (SEO), this research paper explores the vital practice of SEO auditing and optimization. This study examines the many facets of SEO audits using a comprehensive literature review and empirical analysis. It covers technical, content, and off-page optimization components. It also carefully examines how the main search engines' constantly changing algorithms affect SEO tactics. This study assesses the efficacy of several audit techniques and frameworks, gaining knowledge from industry professionals and case studies and providing practical recommendations for companies looking to improve their online presence. This research adds to the body of knowledge on SEO audit and optimization by combining theoretical frameworks with real-world applications. It provides invaluable insights for marketers, business owners, and digital strategists navigating the complexities of online visibility in the modern digital ecosystem. Keywords - SEO Audit, SERP, SEO Optimization.