The lowest and highest prices at which a stock has traded in the previous 52 weeks. The 52-week range is provided in a stock's quote summary along with information such as today's change and year-to-date change. Companies that have been trading for less than a year will still show a 52-week range even though there isn't data for the full range.
Technical analysts compare a stock's current trading price to its 52-week range to get a broad sense of how the stock is doing, as well as how much the stock's price has fluctuated. This information may indicate the potential future range of the stock and how volatile the shares are.