Category Page: 

The best seller products are identified from the products of the current category or including sub-categories on which the best seller is being displayed.

Manufacture Page: 

The best seller products are identified from the products of the current manufacturer on which the best seller is being displayed.

Product Detail Page:

The best seller products are identified from the category(s), product tag(s), manufacturer, and vendor of the current product on which the best seller is being displayed.

Product Tag Page: 

The best seller products are identified from the products mapped with the current product tag in which the best seller is being displayed.

Vendor Page:

The best seller products are identified from the products of the current vendor on which the best seller is being displayed.