Many CRMs use tags to facilitate the selection of groups of people, audiences. Tag is a kind of shortcut: you place a tag-word into a field of the people you think it matters and then you just let the system select every record (person) with that tag.
Other CRMs instead use more complex queries to select audiences:
Let’s imagine you want to find out all the companies (in your CRM) that have bought the service “Business Growth” and they are based in Edinburgh. A query will search into products/services bought fields and select only the company based in the city of Edinburgh.
What is the difference? A tag is a word that you have to decide to place into a field and it will stay there until you delete it. Selection is static, requires a lot of manual work in managing tags for each record. Its benefit is that you do not need to know how to create queries. Users can feel it is a shortcut, as simply selecting the tag they see the selection, but they soon will discover the limit of it as the audience won’t be dynamic.
Simple solutions are not always the right solutions.
Extract from Managing Sales Pipelines with Pipedrive CRM