A Comma Separated Variable (CSV) output file is a common way of exchanging data between systems.
To output a list of contacts who have a particular tag, you need to navigate to the Tag by selecting Contacts - Tag and then select the name of the tag. You can then go into the Tag Log to Export the CSV:
You'll now see a box where you can choose the field data you'd like to export per contact. You must include email as a field, even if you select nothing else.
You can select whichever tags you require. These can be selected by typing in the tag id, or else by selecting the tag name from the pulldown. You must manually select the tag you are viewing, even if you select nothing else.
Once you've made your selection, click the Export contacts button to download your CSV file.
You will receive an email with a link to download your CSV export. This data can be copied and pasted into a text editor for further use.
Note: If you frequently export the same selections, you can save the selection as a preset. Presets can then be loaded from the bottom left corner of the form.
If you want to compare which contacts have some tags but not others, export all the relevant tags in a single export. You can then use a spreadsheet to analyze the date.