From Shopify Wiki
Collections are the primary way of organizing your products, and are meant to complement the tagging system.
If you want to group together a number of products and to have complete control over which products are included, then a custom collection is probably what you are looking for. You can pick any number of products to be included in the collection when you create it, and any time you need to make a change you just need to come back to the Collections tab and add or remove whichever products you want.
There is one custom collection called frontpage which is included automatically when you create your shop. Most themes, as you may have guessed, include this collection on the front page of your shop. It's easy to include products in the frontpage collection because there is a checkbox shown for exactly that purpose when you are editing a product's details.
Here are some other ideas for custom collections that you could put together:
- Staff Favorites: each of your staff members can select a few products that they think are _particularly_ cool to showcase for your customers.
- Living Room, Bathroom, Kitchen: a home furnishing shop could organize its products by room in addition to product type.
- PS3, XBox 360, Wii: if you are selling video games and accessories, then your customers will probably be interested in browsing for only a single system at one time.
These are collections which are filled with products based on simple rules that you define, but the best part about them is that you never need to worry about updating them with new products: unless you want to change the collection's rules, you can just "set it and forget it."
Smart collections can be extremely useful in a variety of different situations. Here are just a few:
- Stocking Stuffers: Product price is less than 20.00.
- Don't delay! Buy now!: Inventory stock is less than 10.
- On Sale: this is a great way of easily putting products on sale and making sure your customers know about it. First, make a smart collection with a single criterion: Compare at price is greater than 0. Then for any product you want to put on sale, just change the product price to whatever you want and put the original in the compare at price field.
- Product Title: Name of the Product
- Product Type: Type of the Product
- Product Vendor: Name of the Vendor
- Product Price: Price of any variant for a given Product
- Compare at Price: Compare at Price of any variant for a given Product
- Weight: Weight of any variant for a given Product
- Inventory Stock: Inventory Stock of any variant for a given Product where the stock levels are being tracked. Variants with untracked stock levels are ignored.
- Variant's Title: For Products that have multiple options, Variant Title is the concatenation of all the variant's option values, separated by " / ". For example, if your product has a "Size" and "Color", and one of your variants has a size of "Large" and color of "Blue", then the Variant Title is "Large / Blue".
For regular products, it is simply the Variant Title.
Automatic collections are created by Shopify for every product type and product vendor that you define. You don't need to do anything extra to create those collections: Shopify does it for you. With most themes, customers will be able to view these collections by following the type and vendor links shown on the product pages.
I added a Collection but it's not showing up. Where is it?
Your customers need a way of seeing your collections. The easiest way to showcase a collection is to make a link to it on the Navigation page. If you ever decide to delete your collection, any links created in this way will automatically be removed as well.
Can I link to a collection from within one of my blogs or pages?
If you have lots of collections, you may run into a problem if you link to all of them from your main menu: your shop's interface could easily get very cluttered, especially if your theme is not specifically built with this in mind.
What about tags?
As you start adding products to your shop, you might wonder about when you should use a tag to describe something and when you should rely on a collection instead. There are no hard and fast rules about this, but there are a few things you should keep in mind.
For any collection which you've made accessible through your shop's interface, your customers will be able to see a list of tags they can select in order to filter that list. If all of your shirts are in the "shirts" collection and you've given them all a "shirt" tag, it could be a bit redundant: your customers will find the option to limit their view of your shirts by only looking at the ones that are, in fact...shirts.
Just put yourself in the customer's shoes and think about what kinds of tags would be most helpful in narrowing your search when you arrive at a collection. Your choice of tags will guide your choice of visible collections, and vice versa.
Take note that tags are case-sensitive. As a result, 'Black' and 'black' are 2 different tags.
The URL of a collection filtered with a tag looks like this:
You can filter a collection with up to 3 tags:
Tags are handleized in the URL and separated by a '+' sign.
For example, Noir chamaré will become noir-chamare.
What about sub-collections?
Shopify has no concept of sub-collections, but there are clever ways in which this can be worked-around: