iPhone – Bigger Keyboard whilst on the Web (Safari)
Tapping on Safari’s address bar summons the on-screen keyboard.
If you rotate the iPhone horizontally before tapping on the address bar, the Safari window will switch to horizontal mode. When you tap on the address bar, the on-screen keyboard will appear horizontally.
It will also be much larger than the standard, vertical keyboard, making data entry a little easier.
If you want to use the keyboard in its standard vertical orientation, summon it before turning your iPhone