Data entry mistakes occur when information is incorrectly inputted into a system, leading to inaccuracies. Common errors include typos, transposed numbers, and incorrect formatting. These mistakes can happen due to human oversight, lack of training, or rushed work environments. Such errors can have significant consequences, especially in fields like finance or healthcare, where precise data is crucial. For instance, a simple mistake in entering a patient's medical record can lead to incorrect treatment. Regular audits and training can help minimize these errors and ensure data integrity.