Since it’s introduction in OS X Leopard, Quick Look has been one of our favourite everyday tools. It’s an incredibly useful way to quickly preview documents, music, and photos, without having to load up the application that would normally run them. If you’ve ever wanted to check how an MP3 sounds, but find the frustration boiling when iTunes suddenly launches after you’ve selected the file, or wanted to take a glance at a Pages document without waiting for the iWorks app to load, then Quick Look will be your new best friend. 
Sadly the feature is often overlooked, as many users are simply unaware of its presence, but once you’ve started using Quick Look you’ll wonder how you ever lived without it. As the feature is built into the operating system it’s always available in the Finder. Just select the file you want to examine and then press the space-bar. This will bring up a window that allows you to look at the file.
If you want to increase the view to full screen then you can click on the arrows symbol in the top right hand corner, you can also launch the relevant app or share the file by clicking on the buttons to the left of the arrows.
It’s not just documents and photos that can utilise this tool, MP3 files are also available, with the ability to play the music directly in the window.
One feature that isn’t turned on by default though is the ability to highlight text within the preview so that you can copy and paste it into another document. Thankfully it is quite easy to enable, although it does require a little bit of typing in the Terminal application. Don’t worry, you won’t be there long and we’re here to guide you through the harrowing world of command line programming.
First of all you’ll need to launch the Terminal interface. To do this go to Finder and click on Applications>Utilities>Terminal.
The small window will open up, awaiting your commands. Simply copy the following text (you can cut and paste it to save typing) into the Terminal window, then press return.
defaults write com.apple.finder QLEnableTextSelection -bool TRUE; killall Finder
Finder will refresh and nothing else will seem to have happened. This is fine, just close the Terminal app and use Finder to locate a text based document (Word, PDF, Pages, etc.). Click the file once to select it, then press Space-bar to bring up the Quick Look preview. Now when you highlight a section in the document you will be able to copy the text just like you would if it was running in a word processor.
You might find that you won’t be able to edit all documents. This could be due to protection within some files, but on the whole it’s a great way to speed up your workflow with only a few clicks.