In some organizations like colleges, schools, The administrator of the organization has blocked some websites include websites about pop culture, health, medicine, women, religion and politics. Social websites are also often blocked and include the likes of Facebook, Twitter, YouTube, Pinterest, Instagram, Reddit, Digg, Hulu, LinkedIn, Tumblr, Blogger (Blogspot), MySpace, Bebo, Flickr, Yahoo! Messenger, Typepad, Technorati.
There will be genuine reasons for which we might want to visit the website blocked at our School, College or Work. Follow any of these methods to get access to it. First three methods are enough to access almost all blocked website. however, you can try all these methods, if a blocked website still cant be accessed. All of these methods worked well when i tried them at my college (JP College of Engineering.)
1. Cache method: Most search engines maintain a cache of web pages indexed by them. You can search for a website on Google , Yahoo! or Bing and click on the cached link that is given next to the result. To load the web pages more quickly, you can visit the text-only version. Since the website is provided from the search engine's servers, it can be used to overcome IP address and URL based filtering.
2. Using Google Mobile Search: For users browsing on a slow mobile internet connection, Google Mobile search removes all CSS styling and JavaScript to present a stripped down version of the web page from Google's own server. As the content is provided from Google's servers, the blocking software feels that you are visiting Google, whereas in reality, you are viewing the blocked website. Go to Google Mobile Search.
3. Access blocked websites with Google Translate. You can use translation service from Google to visit blocked websites. To do so, enter a language different from the website's language in the 'From' field and English in the "To" field. You can also use this method to bypass software that block websites on the basis of specific keyword mentions. Just translate the URL you wish to visit in a different language to overcome the keyword block.
4. Create a 2 layered unblocker: Go to Google Translate, open any proxy website inside it and then use that proxy website to access your blocked website. In this way, you can achieve two layered website unblocking.
5. Use RSS Readers for accessing restricted blogs: All blogs syndicate their content via RSS feeds which you can subscribe to in web based RSS readers like Feedly to access blocked content.
6. To access a blocked website, you can enter its IP address instead of the URL in your browser's address bar. This can bypass most basic forms of website blocks. Although if the blocking software maps the IP address to the website domain, the website will still remain blocked. You can find the IP address of any website by pinging the website domain name in the Command Prompt in Windows (Terminal in other operating systems) and noting its IP address. Execute ping www.google.com in the Command Prompt to ping www.google.com.

7. Use IP Address to Decimal conversion: If you cannot access your blocked website by entering its IP address, you can enter the decimal equivalent of the URL's IP address to get access to it. Search Google for IP to Decimal + IP Address of the banned website and Google will convert it into decimal. Enter that into your browser's address bar and see if the blocked website opens.
8. Nyud.net: To unblock blocked websites, just add nyud.net to their URL. For example, if this blog (www.tweakandtrick.com) is blocked, you can visit it by going to www.google.com.nyud.net.
9. Opera Mini Simulator: Opera Mini, the mobile browser for users with a slow internet connection, can be installed on your computer. You can use this PC version to visit blocked websites as Opera Mini accesses content from Opera's servers instead of accessing it from the servers on which the website is hosted. Most websites will load through this method, although the quality of the results obtained may not be that good for JavaScript heavy websites.
10. TOR: TOR or The Onion Router is a free software that protects the privacy and security of its users by channeling data through multiple nodes so as to prevent the original data from being unscrambled. Although browsing through TOR is a bit slow, it is one of the most effective ways of bypassing restricted websites and protecting your privacy.
11. Proxy websites: There are many proxy websites (anonymizers) which open blocked websites on their servers and present the data to you. This hides the address of the website you are trying to visit from your internet service provider. Few popular free ones include Anonymouse and KProxy.
12. VPN software: VPN or Virtual Private Network software can be described as a tunnel under the public network that offers more anonymity than proxy websites as it also encrypts the data transferred by the blocked website thus, offering complete anonymity. Although most VPN software are available as paid software only,HotSpotShield is a popular free alternative.
13. IP hiding software: Sometimes, websites block users on a particular IP address from visiting themselves. In such cases, free IP hiding software like UltraSurf can be used to visit them. While free software offer very less features as compared to paid ones, they are still effective for overcoming most common blocks.
14. Changing DNS servers: A common way of blocking websites is preventing DNS servers from giving the locations of the blocked website's servers. In such a scenario, changing your DNS servers to those of OpenDNS orGoogle DNS will be your best option to get over the block. As an additional advantage, this can also increase your internet speed.

15. Edit your host files: Some malware and blocking software edit your host files and add a website's address in them to prevent you from visiting it. In such a scenario, you can edit your host file with Notepad by visiting “C:\WINDOWS\system32\drivers\etc” if C is your system drive. In Windows 10, Windows 8(.1), Windows 7, a warning from UAC might be displayed.
Thanks:TweakandTrick