What is Open Access?

When learning about Digital culture,the progression of media and the internet it seems important to consider open access and its advantages alongside its drawbacks. Open access means taking advantage of the global reach and internet publishing to make peer-reviewed scholarly materials freely available. From a university students point of view I might be slightly biased in favour of open access, why should we pay when it can be openly accessed on the web?
http://www.wired.com/opinion/2013/01/we-need-more-than-releasing-articles-to-make-open-access-work/
During my research I came across this blog written by, Dan Cohen which seems to highlight both advantages and disadvantges of open access from varying points of view. He brings up the point that "an open access system can never work on the demand side." Which is true, as long as people can access books and knowledge for free there will be no need to go and out and purchase.
This topic is one that interested me more than I would have thought, if it works and it is easier then why isn't everybody doing it? It seems only some people agree whilst the others are still strongly against.
Open Access brings greater visibility and impact, in todays' society it is far easier for someone to quickly look online for an article or book than it is for them to go a library or book store. Open Access will also help to progress research, it will help to enable better managment and assesment of research. Not only that but it also provides long term document availabilty, if it is put on the internet surley we will always be able to access it?
However some reservations about open access have been brought up, there are certainly reservations amongst some about the quality control and the authenticity. If things are put up on the web, does this mean it is easier for people to change it making the work less reliable? But, for me, the main reservations, particularly for the authors and publishers is the financial issue. With open access the demand decreases, decreasing any profits that could have been made.
In my opinion, after actually looking at the advantages and disadvantages, a part of it must be that our society simply doesn't like change and they are not willing to accept Open Access. But I think open access has to be the future, it will make work available to the world wide web, which will make it fair. Open Access will mean everybody all around the world will have the same access to the same information. I think people should be embracing the idea not turning it down.