Novice SEO Concept: crawling and indexing difference

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Crawling and indexing is the two professional terms of SEO, when many novice contact SEO, they will use these two words mix, think crawling is index. Today, I would like to tell you about some crawling good index between the difference is what?

1, crawling

When the search engine spiders crawling in the site, there is a site and only a URL is crawled, search engines can be traced from other pages of the link tracking crawling to this site, so the understanding of crawling is the search engine according to the link to the site specific URL to crawl.

Perhaps the above concept is more abstract, we illustrate briefly, for example, in many times when spiders crawl site, some of the site links can not be crawled, such as:

(1) The link code is JavaScript, because this is called "spider trap", when crawling sites, spiders will automatically block crawling these links.

(2) The link is marked as robots.txt "forbidden instruction."

(3) Orphaned links (no one hangs in the case of Sitemaps.xml, including links)

(4) the page where the link is located is a page containing the chain nofollow instruction

(5) is to crawl the link, but because the server is not stable reason can not be crawled.

2, Index

Index and crawl The biggest difference is that the index is not a specific URL is crawled, but a lot of songs on the page URL, simply say that when the search engine to determine what page to index, it will be the page of all URLs for processing and crawling, in the process of crawling, Spiders will be based on the content of the page to do the appropriate processing, a simple example, in some of the content of the page although there is a URL but this URL has been added noindex instructions, then the search engine will not crawl this page.

Why the Site page is not indexed:

(1) contains the NOINDEX instruction in the page ()

(2) Duplicate content: pages with the same content may not be indexed.

(3) Other reasons: Link age and link popularity

If the novice wants to know which pages in the site have been indexed, then through the "site+ site domain Name" way to retrieve, through this way, the search engine will show how many pages have been cited by spiders and which pages.

Crawling and indexing Although the spider is said to crawl the site, but they are included in the direction is not the same, here I suggest to distinguish between the attention.

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