Sometimes when typing, you just need the next few letters to be capitalized, for example, “My PC is BROKEN!” or abbreviations like “LMAO.” To do this, use the Shift key on the iPhone just as on a computer: simply hold it down with one finger while you type with another, then let go to go back to normal.
You can also type in all capitals without holding the Shift key. Simply double-tap the key when typing.
The key will now show an extra line under the arrow to signify that caps lock is enabled. Tap once more to disable and type in lower case.