Dating a Gibson acoustic guitar can be done by looking at the serial number. Gibson has used a variety of serial number formats over the years, so it's important to consult a reference guide to ensure accurate dating. The location of the serial number can also vary depending on the model and year of the guitar. Generally, the serial number is stamped on the back of the headstock or inside the soundhole. Once you have located the serial number, you can use it to look up the year and sometimes the month and day of manufacture. Gibson's website has a serial number search tool that can help you date your guitar. Additionally, there are many online resources and reference guides available that can provide more detailed information on dating Gibson guitars.