Unique opens and unique clicks are key email marketing metrics that measure the impact your email has. While the two terms are similar, there is a difference between the two:

• Unique opens is the distinct number of recipients who have opened your email at least once.
• Unique clicks is the distinct number of recipients who have clicked one or more links inside your email.

Tracking both metrics can tell you how users perceive your emails. For example, if you have a high number of unique opens, but a low number of unique clicks, there might be an issue with your email (for example, your viewers consider your subject line misleading).