Sometimes, you have multiple datasets, each with a different geographic coordinate system. While ArcGIS Pro can handle converting or transforming the data on the fly so the datasets show accurately, it requires a lot of processing power for larger datasets that could slow down your drawing performance considerably. It is usually recommended to transform your data into one geographic coordinate system so that you have only one reference to keep track of. Transforming from one geographic coordinate system to another can be tricky as there are many transformation methods available, and each one is specifically designed for specific transformations. For example, transforming from NAD 83 to WGS 84 has seven different methods: