When IAs and taxonomists talk about attributes, we’re most often referring to the properties applied to terms within a Taxonomy. So, for example, in our product Taxonomy within PoolParty (our Taxonomy management system), we have a defined schema of attributes that are applied to all terms in that Taxonomy. Attributes include things like alternate labels for products, product release dates, a canonical URL for that product–any information we want to capture about a given Taxonomy term that can then be used by humans or machines.
All attributes have values. The term “Microsoft Office” in our product Taxonomy has an attribute of “alternate label” with the value of “Office.” Depending on how attributes are defined, they can use either single or multiple values.
A slug is an attribute on all of our Taxonomy terms. Slugs are the machine-readable ID strings that tell our platform how to handle Taxonomy terms. “Microsoft Office” is the preferred label in our Taxonomy, and that is what is displayed in the site UI, but that isn’t readable in the content files, so it has a slug of “microsoft-office.” That is the string that appears in the content files under the “product:” field.