This article outlines how and when to create collections in Shopify stores.
In some cases, it might be helpful or necessary to create product collections in a client's Shopify Store, although, by using Shopify Buy Buttons in conjunction with individual WooCommerce Product pages on a WordPress site, we can better categorize products in a manner that is searchable within the WordPress site, making Collections in Shopify not really necessary.
For more info on collections, read the Shopify support article Collections