URLs
If your client has subsidiaries or sister companies that you want to include in the tracked time for that client, enter them here. eg (toyota-iq-cygnet.com)
You can use URLs to associate seemingly unconnected urls to this client (eg hubspot.monacogptickets.com)
If you are a coding house and you want to include a localhost\projectname\ or a staging site address (clientname.temporarywebsite.com or yourtempserver.clientname.com) here, you can assign that time to the client as well. If you want to separate the dev time from the live support time, enter them as two different clients, each with the appropriate URL (eg Clientname Aston Martin URL: astonmartin.com and Clientname Aston Martin New Site Dev URL: staging.astonmartin.com) because the staging site is only ever seen by your devs, it can be allocated a different hourly rate tag to the live site.