You can filter by one or many categories at once and very quickly pull up a list of results that match all of the tags that you selected.
Follow the steps below to set up your custom dropdown field
1. Select Customize under the "..." on your People or Company grid
2. Add a new column
3. Name the column
4. Select "Hierarchy" as the column type
5. Select if you want this hierarchy field to filter by AND or OR. Filtering by AND will return only people or companies who meet all of your selected criteria. Filtering by OR will return people or companies who meet at least one of your select criteria. You can always come back and change this later depending on the search you want to run!
In your Smart Grid, you will now have a new column:
5. Add custom fields
You can create as many Categories as you would like and you can use them in both of your Smart Grids: People Grid and Companies Grid.
Check out best practices on how to use categorizations here!