Each article can specify one or more topics, like this:

[[article]]
file = "topic.md"
title = "Article topic"
author = "zine-team"
topic = ["advanced", "tutorial"]
pub_date = "2022-12-16"

However, each topic should been declared in the root zine.toml:

[topics]
advanced = { name = "Advanced knowledge", description = "Advanced feature of zine" }
# all of fields are optional
tutorial = {}

Zine will generate a dedicated topic page for each topic, for example:

https://example.com/topic/advanced
https://example.com/topic/tutorial

Also, the user can check all topics in /topics page.