You can use text fields to include notes or any other freeform text in your project.
Text fields can be used in filters, for example: field:"exact text". Text fields and item titles will also be used if you filter for text without specifying a field.
Number fields can also be used in filters. You can use >, >=, <, <=, and .. range queries to filter by a number field. For example: field:5..15 or field:>=20. For more information, see Filtering projects.