A mod APK, short for "modified Android Package," is a modified version of an Android app's installation package. These modifications often entail alterations to the app's code, graphics, or functionality, providing users with additional features, unlocked content, or enhanced capabilities not found in the original version. Mod APKs can offer benefits like unlimited in-game currency, premium features for free, or removing advertisements. However, it's essential to exercise caution when downloading and using mod APKs, as they may not always be authorized by the app developers and could pose security or stability risks to your device.