The year 2018 was a pivotal period in the evolution of modern SEO. With the formal rollout of mobile-first indexing, an emphasis on content trustworthiness, and multiple impactful algorithm updates, Google signaled its ongoing shift toward quality, relevance, and user-centric search experiences. For SEO professionals, it was a year that demanded deeper collaboration between technical teams, content strategists, and brand managers.
Key Algorithm Updates
March 2018 Core Update
This update focused on content relevance and quality signals. It impacted several industries, especially sites with outdated or thin content. Google stated that there was no “fix” for those affected other than continued investment in great content and site improvements.
April 2018 Broad Core Update
This broad update reinforced the trends from March, rewarding sites that had improved E-A-T signals and user engagement metrics. Content with a clear author, up-to-date information, and trustworthy citations performed better.
August 2018 Core Update (Medic Update)
Unofficially dubbed the “Medic Update,” this was the most significant algorithm change of the year. It disproportionately affected health, wellness, medical, and financial websites—sectors under the Your Money or Your Life (YMYL) category.
The update placed a heavy emphasis on:
- Demonstrable expertise and professional credentials
- Trust signals such as reviews, backlinks from authoritative sources, and citations
- Transparent ownership, privacy policies, and editorial standards
While Google never confirmed that it specifically targeted medical content, patterns across ranking data made it clear that trust and accuracy became more influential ranking factors.
Mobile-First Indexing
In March 2018, Google officially began rolling out mobile-first indexing after over a year of experimentation. This marked a shift in how Google crawled and indexed the web. The mobile version of content was now considered the primary version for ranking purposes.
SEO professionals responded by:
- Ensuring mobile parity between content, metadata, and structured data
- Improving mobile performance and page load times
- Prioritizing responsive design over dynamic serving or separate mobile URLs
Mobile-first indexing confirmed that Google aligned with user behavior, as most searches now occurred on mobile devices.
E-A-T Gains Visibility
Although the concept of E-A-T (Expertise, Authoritativeness, and Trustworthiness) was introduced in earlier Google Quality Rater Guidelines, it became a central theme in 2018.
Following the Medic Update, SEOs began prioritizing the following:
- Clear and visible author information, including credentials
- Citations from reputable sources
- Secure domains (HTTPS) and updated privacy policies
- Consistent brand presence and positive reputation across the web
Google’s increased reliance on human quality raters highlighted that trust was not just a content signal, but also a brand and experience signal.
Structured Data and SERP Features
Structured data continued to grow in value. Sites that implemented schema markup for reviews, products, recipes, and local businesses were better positioned to earn rich snippets.
Key schema enhancements in 2018 included:
- FAQ and Q&A formats
- JobPosting schema for career sites
- How-to and recipe markup for content creators
SERPs also evolved to feature more direct answers, People Also Ask sections, and local map packs, reducing the real estate available for traditional organic listings.
Voice Search and Conversational Queries
While still in the early stages, voice search began influencing content strategy. Google Assistant, Alexa, and other smart devices changed how users phrased questions and interacted with information.
SEOs began adapting by:
- Creating content that answered specific questions clearly
- Structuring content using FAQ-style formats
- Targeting long-tail, conversational queries with natural language
Though voice search optimization was not yet mainstream, it became clear that featured snippets and concise, high-trust answers would dominate this emerging channel.
Strategic Takeaways for SEOs
- Trust became a competitive differentiator.
Especially for YMYL topics, E-A-T became a requirement rather than a recommendation. - Mobile-first indexing was a structural shif.t
Technical audits are needed to account for mobile experience as the foundation of Google’s crawling and indexing. - Content required more than keywords
Updates and quality rater feedback emphasized relevance, clarity, and topical authority. - SERP features changed how users interacted with results
SEOs had to optimize for rankings and visual prominence, answer boxes, and structured data-driven features.
Conclusion
2018 was a year of foundation-setting. Google focused on rewarding trustworthy, authoritative content while reinforcing the need for a seamless mobile experience. The Medic Update clarified that user well-being and accuracy were non-negotiable, particularly in industries where misinformation could cause harm.
For SEO professionals, long-term success increasingly depends on collaboration, transparency, and a genuine commitment to user value. The lessons from 2018 remain highly relevant as search continues to evolve toward experience-first discovery.