The exact information encoded in a guitar's serial number varies depending on the manufacturer; however, using an appropriate decoding tool, an approximate year of manufacture is likely to be findable. Other information that can be found from some manufacturers' codes includes the model type and country of manufacture.
A range of expert enthusiast websites provide listings of serial numbers for famous guitar manufacturers such as Fender and Gibson, with tables or tools to allow guitar owners to look up their guitars. These tables give all known information about the guitars within the serial ranges available. However, because of the sporadic nature of the earliest markings on guitars and the lack of standardization in terms of this marking historically and up to the present, there is no guarantee that a particular guitar is included.
For earlier models and guitars from smaller workshops, a date may be marked on the instrument rather than a serial number. However, if this is on the neck, it only signifies the date the neck was created, not the date of completion of the guitar. Similarly, serial numbers that connote a particular date or workshop for one model of guitar may have a completely different meaning from another from the same manufacturer.