Glossary
JSON column formatting
Column formatting is a JSON snippet applied to a SharePoint list column that changes how its value is drawn: colours, icons, progress bars, buttons. It is free, needs no deployment and no IT approval, and any site owner can apply or undo it in minutes.
It should be the first thing tried before paying for anything. Conditional status colours, an icon next to a value, a progress bar from a percentage, a button that opens a form or starts a flow — all of it is free.
Its hard limit is that it sees one item at a time, so it cannot count, sum or average. Counts and KPI tiles are exactly where the free route stops.