Of all these error codes by far the most common is 404 which is also one of the few that can be worked around - always assuming the website has not simply ceased to exist. Everything else can be fixed although it would help to explain the difference between web names as they appear in the press and as they appear in a Browser.
Whenever a company advertises its URL it will take the form of something like WWW.COMPANY.COM, but on the Internet itself such names are more likely to be, perhaps, WWW.COMPANY.COM/ SOMETHING/ SOMETHINGELSE/. All this really means is that the website is split up into several directories (also known as domains) which could themselves have sub-directories, each one holding different files. Typically this would be to separate different sets of information into logical groupings with the forward slash (/) being there to signify the different directories. Under this system the URL of the website as a whole is simply the part that ends .com or .co.uk or something similar. The URL of a particular page on that website is the complete path to it. including all directories and sub-directories. (The names that are separated by a forward slash.)
Knowing this it becomes easy to work around error code 404. Start by entering the URL for the website as a whole (The .com or .co.uk name). If that produces the error code the website is no longer in existence so stop looking. However if this does give access to a website the easiest way of solving the problem is to use the links built into it to navigate to the right page. At which point the Browser will display the long and complicated web page URL. Should this not be possible, or just not obvious, and there are sites where this is true then add the next directory name to the URL in the Browser and repeat the process. Here a little bit of care has to be taken as sometimes entering one name into a Browser causes it to delete the name that was there previously, which in this case means the URL of the website itself. Usually this can be prevented by moving the cursor to the point where the next directory is to be entered and clicking the left mouse button. The next directory can then be safely entered (but remember to include the forward slash).