Do you want to make a local copy of a web site for future reference? (Perhaps your boss has asked you to copy the internet to his laptop, for his convenience, for example). Well, for a specified site, that task is relatively straightforward with wget - which you can easily find on Linux, on Windows as part of Cygwin, and OS X as an add-on.
Here is the synax of the command to download this web site:
wget --mirror -w 1 -p --html-extension --convert-links -P ./ http://wwww.themolecularuniverse.com
The options here are:
'-mirror' get a copy of everything on the site
'-w 1' wait for 1 second for each page - this is optional and reduces the load on the site
'-p' get the prerequisites for the page - this means that linked graphics files, for example, will be downloaded too
'--html-extension' change any files which don't have an html extension to html
'--convert-links' make links in retrieved documents point to their local versions
'-P ./' put the retrieved files into the current working directory
wget can be very helpful...but of course you will just acquire a static copy of the target site and you will not get updates, enhancements, or corrections!