Search Engine Optimization (SEO) in Online Marketing: A Systematic Literature Review

Abstract

Search Engine Optimization (SEO) has become a key element of digital marketing, shaping organic visibility, brand credibility, and customer acquisition. This study presents a systematic literature review (SLR) of SEO research published between 2016 and 2022, focusing on ranking determinants, semantic optimization, cross industry applications, and evaluation metrics. Findings show that on page and off-page factors such as content quality, keyword placement, backlinks, and user engagement remain dominant drivers of rankings, though their influence varies across industries. Semantic SEO, through structured data markup and entity based content, is gaining relevance, but its direct impact on business metrics like conversion rate and customer lifetime value is still underexplored. SEO also extends beyond e-commerce, influencing journalism and academia by reshaping practices for visibility and knowledge dissemination. A growing trend is the integration of SEO indicators with business metrics to align tactical practices with strategic objectives. Despite these developments, gaps remain in standardizing ranking factors, measuring the business value of semantic SEO, and developing integrated evaluation models. These findings emphasize SEO’s dual role as both a technical and strategic discipline and highlight the need for further research to strengthen its academic and practical foundations.