The Art of SEO, 3rd Edition

CHAPTER TWO

Search Engine Basics

In this chapter, we will begin to explore how search engines work. Building a strong foundation on this topic is essential to understanding the SEO practitioner’s craft.

As we discussed in Chapter 1, people have become accustomed to receiving nearly instantaneous answers from search engines after they have submitted a search query. In Chapter 1 we also discussed the volume of queries (more than 7,500 per second). As early as 2008, Google knew about 1 trillion pages on the Web.¹ At SMX Advanced in Seattle in 2014, Google’s Gary Illyes stated that Google now knows about 30,000 trillion pages on the Web. The scale of the Internet/Web (sometimes called the Interwebs) is growing fast!

Underlying the enormous problem of processing all these pages is the complex nature of the Web itself. Web pages include text, video, images, and more. It’s easy for humans to understand these and to transition seamlessly between them, but software lacks the intelligence we take for granted. This limitation and others affect how search engines understand the web pages they come across. We’ll discuss some of these limitations in this chapter.

Of course, this is an ever-changing landscape. The search engines continuously invest in improving their ability to process the content of web pages. For example, advances in image and video search have enabled search engines to inch closer to human-like understanding, a topic that will be explored more in the section “Vertical Search ...