Tags are a great way to add searchable, sortable, filterable attributes to your products.
The Simple Case of Single Values:
When adding a tag to a product, the ideal structure is to create a single-valued key:value pair. For example, Color:Blue or Size:Medium.
Note: Each tag you create for a product will be stored by Shopify and will be available to all products in your store should you desire to add that tag to any other product.
Which delimiter should I use?
We strongly recommend using the colon (:) as your delimiter. As an additional comment, while it is common practice to type the key:value pair with no spaces, key: value, with a space after the colon, is also acceptable.
What if my product has multiple values I want to associate with it?
The ideal structure for providing multiple values for a product (say for a product that is available in both Red and Blue color options) is to add tags with the following structure:
While it may seem more intuitive to create Color:Red,Blue to hold both color values for your product, it creates more tags for Shopify to store, as the tag Color:Red,Blue will be retained as a tag in addition to Color:Red and Color:Blue.
By keeping to a small list of single-valued color options that can be 'tagged' to your product, you can have several products with multiple colors attributed to them.
This same principle applies to any attribute you may want to add to your products. Fabrics, Weights, Materials, etc., can all be created in like manner. By creating a tag for each option that can be applied to a product you limit the number of tags that Shopify needs to store. Multiple tags can then be applied to any product.
What if my attributes are more than one word long or contain weird characters?
Spaces, underlines, dashes and slashes are all allowed in labels and values for your tags. For example: Thread_Size, Thread-Size, and Thread Size are all legitimate labels and Aqua Marine, Aqua_Marine, and Aqua-Marine are all legitimate values. However...
CONSISTENCY, CONSISTENCY, CONSISTENCY
When creating tag labels and values consistency is the most important thing. Color, color, and COLOR are 3 different words to a computer. So, whether you chose to capitalize, use spaces, underlines, dashes or slashes, be consistent!
How will the value display as a facet?
In creating values for your tags, they should be created the way you want them to be viewed on your website. The tag label (i.e. 'Thread Size') will not be seen and so can be formatted in all caps (THREAD SIZE). The value, however, (i.e. 3/4") should be exactly how you would like it to display in your facets list on your live site. So, THREAD SIZE: 3/4-inch will display as '3/4-inch' on your website. If you want 3/4" to be viewed the tag needs to be formatted as THREAD SIZE: 3/4".