Hidden fees refer to additional charges or costs that are not openly disclosed or easily noticeable upfront. These fees are often added to the original price of a product or service, catching consumers off guard and leading to unexpected expenses. Hidden fees can be found in various industries, such as banking, telecommunications, travel, and online shopping. They can include administrative fees, service charges, convenience fees, or surcharges, among others. It is important for consumers to be vigilant and read the fine print to avoid being surprised by hidden fees and to make informed purchasing decisions.