Rounding errors occur when numbers are approximated to make calculations simpler. For example, if you round the number 3.14 to 3, you lose some precision. This can lead to small discrepancies in results, especially when calculations involve multiple steps or large datasets. These errors are common in computer programming and scientific calculations, where exact values are often impractical. When using floating-point arithmetic, computers may not represent certain numbers accurately, leading to cumulative rounding errors that can affect the final outcome of calculations.