Which type of SIM card does the Samsung Galaxy S4 use?
The Samsung Galaxy S4 uses a micro SIM card. This is the type of SIM card that is only slightly larger than the gold chip on the SIM card
Your Samsung Galaxy S4 should have been supplied with a micro SIM card by your network provider, but if it was not they should be able to supply one free of charge if you get in touch with them.
If you are looking for instructions on how to insert a microSIM you may find the video below useful. In the video a Samsung Galaxy S3 is shown rather than an S4, but the same information is still applicable.