Unit 2.1

Fundamentals of Search Engines

Digital Marketing Course

Lecture Duration: 1h 15m

Today's Learning Objectives 🎯

By the end of this session, you will be able to:

✅ Define the three core functions of a search engine.
✅ Explain the process of web crawling and indexing.
✅ Identify the primary factors that influence search engine ranking.
✅ Relate these fundamentals to a basic SEO strategy.

The Digital Gateway

Search engines are the modern library, map, and marketplace, all in one. They are the primary way people find information online.

Google

~91% Market Share

Bing

~3% Market Share

Others

(DuckDuckGo, etc.)

⚡ To be found online, you must first understand how search engines work.

The 3 Core Functions

Every search engine, regardless of its size, performs three primary tasks:

1. Crawling 🔍

Discovering Content

2. Indexing 📚

Storing & Organizing

3. Ranking 📊

Ordering by Relevance

Think of it as: Discover → Catalogue → Recommend

Core Function 1: Crawling 🔍

Crawling: The discovery process where automated programs ("crawlers" or "spiders") follow links to find new and updated content on the web.

Crawlers are constantly scanning the web, 24/7.
They start with a list of known web pages and follow hyperlinks from those pages to discover new ones.
This process creates a massive, interconnected map of the web.

Core Function 2: Indexing 📚

Indexing: The process of analyzing, storing, and organizing crawled content into a massive database called an "index."

The index is like a giant digital library for the internet.

When you search, you are querying this pre-sorted index, not the entire live web.

⚡ Crucial Point: If a page is not in the index, it is invisible to the search engine and cannot rank for any query.

Index vs. The Live Web

The Index (A Saved Copy)

A snapshot of the web, stored and organized.
Extremely fast to search.
What search engines actually query.

The Live Web

Dynamic and constantly changing.
Too vast and slow to search in real-time.
The source from which the index is built.

Core Function 3: Ranking 📊

Ranking: The process of sorting through the indexed pages to provide the most relevant, useful results for a user's search query.

The search engine's algorithm makes this decision in a fraction of a second.

It uses hundreds of different "ranking factors" or signals to determine the order of the results.

Key Ranking Factors (A Preview)

While the exact algorithm is a secret, we know some of the most important signals:

Keywords: How well the content matches the words used in the search.
Content Quality: The depth, accuracy, originality, and value of the information.

Backlinks: Links from other reputable websites, acting as "votes of confidence."
User Experience: Page speed, mobile-friendliness, and ease of navigation.

Practical Application: SEO in Nepal

Example: A Hotel in Pokhara

1. Crawling: The hotel's website must have a logical structure and a sitemap file so Google's crawler can easily find the homepage, room descriptions, booking page, and blog posts about Lakeside.

2. Indexing: Each page's content (text, images of Phewa Lake, room amenities) must be clear so Google can understand it and catalogue it under terms like "hotel in Pokhara," "Lakeside accommodation," etc.

3. Ranking: To rank high, the site needs quality photos, detailed descriptions, fast loading times, and positive reviews (backlinks) from travel blogs or booking sites.

Key Takeaways

✅ Search engines function through a three-step process: Crawl, Index, and Rank.
✅ Crawling is about discovery, and Indexing is about organizing that discovery into a searchable library.
✅ Ranking is the complex process of ordering search results based on hundreds of factors to determine relevance and quality.
✅ To succeed in SEO, you must first make it easy for search engines to find, understand, and trust your content.

Thank You

Questions?

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Unit 2.2: On-Page SEO Essentials

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