How many time it happen that you try to open a site but you will get some error and unable to access that site,The reason for this could be anything like your Internet connection is not working properly or the server of site may be down.
By using DownForEveryOneOrJustMe site you could find out that is really that site is not working or it is having problem with you only.
All you need to do it just visit that site from HERE and put the url there and hit Enter within few seconds it will tell you is that site down for everyone or just for you.