What's the most significant change you've seen in SEO over the past 15 years?

Over the past 15 years, the most significant change in SEO has been the shift from keyword-centric strategies to a more holistic approach that emphasizes user experience, content quality, and semantic search. Here are some key aspects of this transformation:

1. Algorithm Updates: Google’s major algorithm updates, such as Panda, Penguin, Hummingbird, and RankBrain, have continuously refined the way search results are ranked. These updates penalized low-quality content and spammy link-building practices while rewarding high-quality, relevant content and natural backlink profiles.

2. User Intent and Semantic Search: The focus has shifted to understanding the intent behind search queries and providing the most relevant results. Google's Hummingbird and subsequent advancements in natural language processing (NLP) have played a crucial role in this. Instead of just matching keywords, search engines now interpret the context and semantics of queries to deliver more accurate results.

3. Mobile-First Indexing: With the increasing use of mobile devices, Google shifted to mobile-first indexing, meaning that the mobile version of a site is considered the primary version for ranking purposes. This change underscores the importance of mobile-friendly design and performance.

4. Voice Search: The rise of voice-activated assistants like Siri, Alexa, and Google Assistant has introduced new SEO considerations. Voice search queries are often longer and more conversational, prompting SEOs to optimize for natural language and question-based queries.

5. Core Web Vitals and Page Experience: Google's introduction of Core Web Vitals as ranking factors highlights the importance of user experience metrics, such as page loading speed, interactivity, and visual stability. A fast, smooth, and visually stable site is now critical for SEO success.

6. Local SEO: The growth of local search, driven by mobile usage and “near me” searches, has made local SEO a key area of focus. Optimizing for local search involves claiming and optimizing Google My Business listings, generating local reviews, and ensuring consistent NAP (Name, Address, Phone number) information across directories.

7. Content Quality and E-A-T: Google emphasizes Expertise, Authoritativeness, and Trustworthiness (E-A-T) as critical factors for content ranking. High-quality, authoritative content that meets user needs and is created by credible authors is prioritized in search results.

8. Structured Data and Rich Snippets: The use of structured data and schema markup helps search engines understand content better and display rich snippets in search results. This can improve visibility and click-through rates.

9. Integration with Other Marketing Channels: SEO is no longer an isolated discipline. It integrates closely with social media, content marketing, and PPC campaigns. A cohesive strategy that aligns SEO with other digital marketing efforts is essential for comprehensive online visibility.

These changes reflect a broader evolution in SEO from technical manipulation to a more user-centric, content-driven approach. The goal is to provide users with the best possible experience and the most relevant information, aligning with search engines’ ultimate mission of organizing and making the world's information accessible and useful.