You can categorise contacts by adding tags to them. Tags will make your contact management easier. If you add a tag to an organisation, it will also be added to people associated with the organisation.
This means: Always tag the organisation first.
You can add tags when you view a contact in the “Add tags” field on the right hand side. Any tags you add need to be at least three characters long. You can add it by pressing enter or tab.
If you want to delete tags, just click on the “x” inside the tag.
You can search for tags in the contacts overview.
Hint: Use catchy tags, so you will still remember their meaning in a few months.