Why are sites blocked?
Not all sites are blocked for a similar reasons!
Even in countries which are known for internet freedom, we experience internet censorship to a exact degree. It's many times stuff that peculiar americans wouldn't want to browse anyway, so I won't list all the perverted stuff that North American and European countries block. As you move east though, many nations in Africa, the Middle East, and Asia block social networking and media sites like Wikipedia, Facebook, Twitter, YouTube, Gmail, and censor search results. Though they label it national security, it's just plain ancient censorship.
If you utilize the internet at college or work you know what this is. Your place of work or school wifi will in general block time wasting sites like games, chat sites, and they'll in general have a listing of sites which are namely banned on the network. Using wifi in your regional cafe and other shared networks might have banned sites.
Sometimes the sites block foreign IP addresses. This is known as geo-restriction. Some famous sites that engage in geo-restriction are Netflix, Hulu, Pandora, and BBC iPlayer. Lots of different streaming sites do the same element, but I don't know their explicit names because I don't watch Japanese or German TV. Believe me, they exist, and trust me, without an accepted IP, you can't access the web page's content.
How to Unblock Them
Proxies are pleasant for bypassing network restrictions and bypassing internet censorship in some cases. This will depend on the anonymity level of the proxy, and level of restriction placed on you by your ISP or the network. For example, proxies are great for accessing blocked forums and other news related sites at work and school. They don't work so well in China, or for accessing websites with Flash, including Facebook and YouTube. Some proxies can. Most proxies won't be able to bypass geo-restrictions.
Though I did not make proxies sound too beautiful, I only mean to make the point that MOST aren't great, and have limited capabilities as far as unblocking websites on your iPhone and iPad. There are some proxies for iPhone and iPad that unblock Facebook, YouTube, and even encrypt your data to hold your information private. Some are from reputable sources, and work almost about as pleasant as VPNs. The main profit? They're inexpensive. The second main profit? You don't need to install anything – they work directly from your web browser.
In case you did not catch that, I prefer VPNs to proxies. They unblock more sites, and I feel like it's in a more convenient way. You simply connect to a private VPN server provided by a VPN service, and leave the VPN running in the background of your iPhone or iPad. People in business, education, and even the military use them for privacy and security. It's like using a private internet inside of the public internet. You can still access your favorite sites, but privately and securely.
The element that you're concerned with optimum is surfing blocked sites though, correct? VPNs provide you with the profit of being able to unblock more sites. For one, they unblock geo-restricted sites in optimum cases (unlike proxies, which rarely do). They allow you to exploit other apps and software outdoor your browser with the VPN IP handle. That means you can unblock gaming sites, and play non browser based games with your accepted IP.
Popular VPN sites available on the internet will many times offer L2TP and PPTP VPN. L2TP is a more private and preserve VPN, but uses more bandwidth, so might not be the simplest choice for streaming, downloading, or gaming. PPTP VPN for iPhone will still change your IP, bypass firewalls, and unblock sites, but it requires less work on your part, and less bandwidth to run. Try both and see what works best for you.