As I understand it, this is mostly done so that you have faster loading times when you visit that website again.
But storing data fills up space. I never, ever cleared this out before, but after reading about it I decided to give it a try and I was astounded at all the data that was sitting there. I did a full sweep and dumped it all.
How to Delete the Stored Website Data on your iPhone with iOS7:
Go to Settings > Safari
Now go way way down to the bottom and click on Advanced
At this point, you’ll see the option to tap on Website Data
Now you get to see all the space that the stored data is taking up.
IF you want to delete it, just scroll all the way down to the bottom and “delete all website data.”
(Or you can delete them individually, as well, by sliding your finger from right to left.)
I was astounded at the length of my list. I emptied it. I probably won’t do it again for a long long time, because I don’t think it was causing any problems whatsoever.
But I’m glad I know how to do it IF I want to do it.
And now you do, too. :)