On a single sitemap.xml file you can include maximum 50,000 URLs. Further, the sitemap file should not exceed 10 Mb in size. Compressing the file to overcome this limitation will not help. The uncompressed version should not exceed 10 Mb. Thus, when you have a significantly large website, multiple sitemaps come to your rescue.
As you know that a sitemap is essentially an index of your web pages. When you create multiple sitemaps, you group them all together using an index of indexes. And this index of indexes is referred as the sitemap index file.
The Sitemap index file contains reference to all your individual sitemap files. The XML format for a sitemap index file is syntactically similar to that of a sitemap file, except that instead of containing your web page urls, it contains urls of your sitemap files. And those individual sitemap files in turn contain your web page urls.
Here is the explanation of the tags that you see in the above example.
The Sitemap index file…
Note that you should not include any page urls in the sitemap index file. Also, all sitemap urls included in the sitemap index file must belong to the same domain and should be hosted within the same hosting account. If you have any special characters in your individual sitemap urls, make sure to escape it by enclosing the url within a CDATA section. (read about how to build a basic sitemap first before reading this article).
To keep matters simple, it is recommended that you place all your sitemap related files under the home directory of your website. Though there are other options available, which can be understood by digging deep into the concept of sitemaps.
CEO, Computer Solutions
Rajeev Kumar is the primary author of How2Lab. He is a B.Tech. from IIT Kanpur with several years of experience in IT education and Software development. He has taught a wide spectrum of people including fresh young talents, students of XLRI, industry professionals, and govt. officials.
Rajeev has founded Computer Solutions & WebServicesWorldwide.com, and has hands-on experience of building variety of web applications and portals, that include - SAAS based ERP & e-commerce systems, independent B2B, B2C, Matrimonial & Job portals, and many more.