Setting discount usage limits protects your margins and profitability. Discount usage limits apply to individual codes within the discount set.
There are two types of discount limits:
"Limit number of times each code can be used in total" will allow each code within the set to be used a defined number of times.
If this is set to one, each discount code within the set can only be used once.
"Limit to one use per customer" limits usage based on a customer's email address.