Most batteries have expiration date codes, indicated by stamps on either the battery itself or on the packaging. Expiration dates differ from the date of manufacture, so users must be aware of which one they are viewing. Batteries that don't typically display expiration dates are button cells and rechargeable batteries.
As of 2015, most brands of batteries are stamped with the month and year that each battery expires, which indicates the time period in which the manufacturer guarantees it to function at full capacity.
In addition to the expiration date, some brands stamp a date code for the time the battery was manufactured. Though some clearly state the actual date, others use a more complicated code. For example, Duracell batteries with a six-digit code indicate the year, month, day and manufacturing plant using a series of numbers and letters with predetermined values.