External storage has changed. It used to be "/sdcard". As mobile phone ROMs become larger and larger, there is no need to install an sd card. The real paths have become /storage/sdcard0 and /storage/sdcard1, which are the SD card and the ROM that comes with the phone. However, during this transition period, /sdcard was used to add a shortcut link to the subsequent real path, but not all mobile phones have this link.
External storage has changed. It used to be "/sdcard". As mobile phone ROMs become larger and larger, there is no need to install an sd card. The real paths have become /storage/sdcard0 and /storage/sdcard1, which are the SD card and the ROM that comes with the phone. However, during this transition period, /sdcard was used to add a shortcut link to the subsequent real path, but not all mobile phones have this link.