What is the key difference between a 'lookalike' audience and a 'custom' audience within the Microsoft Advertising platform, and how do they affect campaign reach for Live.com?

The key difference between a 'custom' audience and a 'lookalike' audience within the Microsoft Advertising platform lies in how the audience is defined. A 'custom' audience is built directly from your own first-party data, such as a list of existing Live.com customers' email addresses or phone numbers uploaded to the platform. You are directly targeting individuals you already have....