How does Google Search work?

Summary

In this informative video, Matt Cutts from Google explains the intricacies of Google's search engine operations, focusing on crawling, indexing, and ranking. He details how Google crawls the web comprehensively, using PageRank as a primary determinant to prioritize sites. The indexing process organizes words in document order, allowing for efficient search queries. Cutts also touches on the evolution from the 'Google dance' to daily crawls for freshness and the use of over 200 factors in ranking, emphasizing the balance between authority and relevance. The video offers insights into Google's infrastructure and the speed at which it processes searches, all within half a second.

Takeaways

• 🌐 Google's ranking and website evaluation process is comprehensive and involves crawling, indexing, and ranking.
• 🕸️ Crawling the web is complex and involves determining the order of pages to crawl based on PageRank and reputation.
• 🔄 The old Google dance was a result of the crawling and indexing process taking approximately 30 days.
• 📅 Google transitioned to daily crawling in 2003 with Update Fritz to keep the index more up-to-date.
• 🔄 Incremental updates to the index mean Google can quickly find and incorporate new updates.
• 📚 Indexing involves taking words from documents and creating an order of documents for each word.
• 🔍 Document selection and ranking involve using over 200 factors, including PageRank and word proximity.
• 🏆 The goal of ranking is to find reputable documents that are also relevant to the search query.
• 💻 Google's search process involves parallel processing across hundreds of machines to find the best match for a query.
• 🕒 Google aims to return search results, including a useful snippet, in under half a second.
• 📈 For those interested in search engine workings, Google offers resources and job opportunities to learn more.

Q & A

What are the three main aspects Matt Cutts mentions as crucial for being the world's best search engine?

Matt Cutts mentions that to be the world's best search engine, one must crawl the web comprehensively and deeply, index those pages, and then rank or serve those pages by returning the most relevant ones first.

How does Google determine the order in which it crawls web pages?

Google uses PageRank as the primary determinant for crawling order. Pages with more PageRank, meaning more reputable links from other sites, are more likely to be discovered and crawled earlier in the process.

What was the 'Google dance' and why was it a problem?

The 'Google dance' referred to the period when Google would crawl for several weeks, then index for about a week, and finally push the data out, which could take another week. This meant that the search results could be outdated, as it took a long time to refresh the entire index.

What significant update changed Google's crawling strategy?

In 2003, Google implemented an update called Update Fritz, which allowed them to crawl a significant chunk of the web every day, leading to a more incremental and up-to-date index.

How does Google ensure that its index remains fresh?

Google breaks the web into segments and refreshes each segment every night, ensuring that the main base index is not significantly out of date. This strategy allows Google to quickly find and index updates.

What is the difference between the main index and the supplemental index mentioned by Matt Cutts?

The main index contains fresh content that is crawled and refreshed more frequently, while the supplemental index contains a larger number of documents that are not refreshed as often.

How does Google's indexing process work?

Indexing involves taking the words in a document and recording in which documents each word appears. This reverses the order from document-centric to word-centric, allowing Google to quickly identify documents containing specific search terms.

What factors does Google consider when ranking search results?

Google uses over 200 factors in its rankings, including PageRank and the reputation of the document, as well as the proximity of search terms on the page, to determine the most relevant documents for a given query.

How does Google handle a search query?

When a user types in a query, Google sends the request to hundreds of machines that search through their fraction of the indexed web. These machines return potential matches, and Google then determines the best page to display, often in under half a second.

What is the role of snippets in Google search results?

Snippets provide context for the search terms within the document, helping users understand why a particular page is relevant to their query and improving the user experience.

How can someone learn more about how search engines work?

Matt Cutts suggests that interested individuals can read academic papers and articles about Google, PageRank, and search engine operations. Additionally, he mentions that job opportunities at Google could provide deeper insights into search engine mechanics.