Gluing – SEO WIKI
Gluing is a combination of two or more sites in the index of search engines. Most often, these sites are mirrors and contain the same content. Bonding can occur both in automatic mode, when search engines independently determine mirrors, and in manual mode, when the webmaster independently indicates which sites should be glued.
Bonding is one of the important parameters in SEO, since this process allows you to leave one of the site options (with www or without www) in the delivery, transfer the popularity and TIC and PR indicators from one mirror to another, and can also serve as an additional insurance for the site.
The user is redirected to the main site from the mirror through the 301 redirect, which is set in the robots.txt file.
Automatic splicing occurs when search engines find identical sites, if they are affiliates or there is a lot of duplicate content (then only relevant pages are displayed, and a copy-paste filter is applied to others).
Bonding checks are performed differently for different search engines. For Google there is a directive “info:”, and in Yandex you can identify the gluing by checking the TCI through Yandex: Catalog.