To add error bars in Microsoft Excel, you need to create a chart. After that, click on the chart to activate it. Then, click the “+” button, which is called “Chart Elements,” located beside the chart. There, you can check the option for “Error Bars.” There are standard options, like “Standard Error,” “Percentage,” and “Standard Deviation.” For more options, you can click “More Options” and enter your values. Error bars can help you illustrate the uncertainty in your data, and they can make your charts more informative.