The library
Attributes such as Colour or Size are defined once here and attached to products. The page is an accordion: open an attribute to see and manage its values.
The search box above the list finds attributes by name or slug, and by their values: type "Intel" and the attribute holding it appears with its matching values listed under the name, highlighted when you open it. Persian and Arabic spellings (ی/ي, ک/ك), half-spaces and Persian digits all match. Escape clears it.
An attribute has a Name, an optional Slug (used in storefront filter links like ?color=red), a Type and a Sort Order. Types: Select, Text, Color and Number. A value has a Label, a unique Slug, an optional Image, a Sort Order, a colour for Color attributes (#RRGGBB) and an optional hover tooltip.
Number attributes
A Number attribute has no values: the customer types it on the product page, within a Min and Max you set, and can be required. It can never be used for variations.
On a product
In the product's Attributes tab you attach attributes (or add a custom per-product one), pick values, and choose Visible on product page, Used for variations and Show in feature blocks. A variation attribute is always visible. Press Save Attributes separately from the product Save.
Conditions show an attribute only when another one has certain values. They cannot reference themselves, form a cycle, or give one value two rules.
A global attribute on a published product becomes a storefront filter. Custom attributes do not. The filter offers only the values that published products in that category (or on that brand's page) use, so a value no product there has never leads to an empty page.
An attribute marked Only as a store filter (a Filter only badge in the list) is offered in the store sidebar but not listed in the product page's specifications or the product feeds, unless the product uses it for variations. Use it for a value that helps a shopper find a product without describing it, such as a range like "13 to 14 inch" when the page already lists the exact size.
Deleting
An attribute cannot be deleted while any product uses it, and a value cannot be deleted while any variation or product option uses it. Remove it from the products first.