iPhone: Safari Web Settings
By default, Safari is set to show some of the features of the web, like some movies, animation, and web applications. You may wish to turn off some of these features to help protect your privacy and iPhone from possible security risks on the Internet.
To change security settings
From the Home screen choose Settings > Safari, then do one of the following:
To enable or disable plug-ins, turn Plug-ins on or off.
Plug-ins allow Safari to display certain videos.
To set whether Safari accepts cookies, tap Accept Cookies and choose "Never", "From visited", or "Always".
A cookie is a piece of data that a website puts on iPhone so the website can remember you when you visit again. That way, webpages can be customized for you based on information you may have provided.
Some pages won’t work correctly unless iPhone is set to accept cookies.
To clear all cookies from Safari, tap Clear Cookies.
To clear the browser cache, tap Clear Cache.
The browser cache stores the content of pages so the pages open faster the next time you visit them. If a page you open isn’t showing new content, clearing the cache may help.