The scenario here is, for example, you are calling your Contacts and recording data via webform using webform_civicrm, and you are using a View to get your list of contacts. On that View you have a link adds the Contact ID (cid) in the url so that person's name etc will load up on the webform.
In this case we also want to have some other information about them, such as their Donation History.
To achieve this we need to build a View Block using a Contextual filter that looks for the contact ID in the url (and doesn't show anything if we do not have a cid available)


