A reader asks: Which iPhone model do I have? Where to find the model number?
Most often, the quickest way to tell which iPhone model you have is to look on the back of the phone. There, you'll see some small text that says something like "Model A1661".
You can also get model details by opening up the Settings app and tapping on General > About. Additionally, you could figure out the size of memory your phone has by tapping General > About > Capacity in the Settings app.
One other way to check is by connecting your phone to iTunes. There you can click on the phone icon to reveal your model number and memory.
Here's a list of all the iPhone models to date:
A1865 - iPhone X
A1901 - iPhone X
A1864 - iPhone 8 Plus
A1897 - iPhone 8 Plus
A1863 - iPhone 8
A1905 - iPhone 8
A1661 - iPhone 7 Plus
A1784 - iPhone 7 Plus
A1785 - iPhone 7 Plus
A1786 - iPhone 7 Plus
A1660 - iPhone 7
A1778 - iPhone 7
A1779 - iPhone 7
A1780 - iPhone 7
A1662 - iPhone SE
A1723 - iPhone SE
A1724 - iPhone SE
A1634 - iPhone 6S Plus
A1687 - iPhone 6S Plus
A1690 - iPhone 6S Plus
A1699 - iPhone 6S Plus
A1633 - iPhone 6S
A1688 - iPhone 6S
A1691 - iPhone 6S
A1700 - iPhone 6S
A1522 - iPhone 6 Plus
A1524 - iPhone 6 Plus
A1593 - iPhone 6 Plus
A1549 - iPhone 6
A1586 - iPhone 6
A1589 - iPhone 6
A1453 - iPhone 5s
A1457 - iPhone 5s
A1518 - iPhone 5s
A1528 - iPhone 5s
A1530 - iPhone 5s
A1533 - iPhone 5s
A1456 - iPhone 5c
A1507 - iPhone 5c
A1516 - iPhone 5c
A1526 - iPhone 5c
A1529 - iPhone 5c
A1532 - iPhone 5c
A1428 - iPhone 5
A1429 - iPhone 5
A1442 - iPhone 5
A1387 - iPhone 4S
A1431 - iPhone 4S
A1332 - iPhone 4
A1349 - iPhone 4
A1303 - iPhone 3GS
A1325 - iPhone 3GS
A1241 - iPhone 3G
A1324 - iPhone 3G
A1203 - iPhone (the original)