Transferring save data to a new Switch ensures you don’t lose progress. First, ensure both consoles are connected to Wi-Fi and logged into the same Nintendo Account. On the old console, go to 'System Settings' > 'Data Management' > 'Transfer Your Save Data' > 'Send Save Data to Another Console'. On the new console, select 'Receive Save Data from Another Console'. Follow the on-screen prompts—both consoles will connect wirelessly. Select the games whose save data you want to transfer, then wait for the process to complete (takes a few minutes). For games that support cloud saves (Switch Online subscribers), you can also download save data from the cloud on the new console: go to 'System Settings' > 'Data Management' > 'Save Data Cloud' > 'Download Save Data'. Note that some games (e.g., 'Animal Crossing: New Horizons') require a separate transfer tool available on the eShop.