Creative Commons, or CC, Licenses are a simple way of letting people know what the rights holder is happy for them to do with the work. Think of them as an extension to what you can already do under copyright law: for example, any restrictions imposed by a CC License, or the complete absence of a licence on a work, cannot override your right to use reasonable amounts of a work in an academic context.
There are several different licences, with names like CC BY, CC BY-ND, and so on, sometimes with a version number attached, e.g., CC BY-ND 4.0 If you find a work (a photo, video, webpage, or whatever) that references one of these licenses by a statement such as "This work is openly licensed via CC BY 4.0" then you will probably be able to re-use the work, but you will need to consult the details about Creative Commons Licenses to find out exactly what you can do, as there are some restrictions:
I have decided that I want to illustrate this guide with a photo of a library, and I found this photograph of the State Library of New South Wales online. The webpage where I found it had some of the CC icons displayed, indicating what licenses were applied, and helpfully included a link to the exact details of the licence terms: CC BY-NC 2.0.
Under the terms of that licence, I cannot use the photo for a commercial purpose. My judgement is that, whatever the commercial status of the University, the link between this guide and any money-making is tenuous, so I think it is ok to use it here as far as the non-commercial restriction is concerned.
Also under the license I must give a reasonable attribution. Having consulted the CC best practice guidelines on attribution, I have decided upon an attribution that includes TASL - Title, Author, Source, and License:
Though similar, the requirement to attribute works used under a CC License and the requirement to reference any works you use in an academic piece of work are not the same thing. Even if you quote or copy a work that says you can re-use it without attributing the source, you would still need to reference it in your academic work.
But probably it would make more sense to illustrate the guide with a picture of Solent Library. My colleague has taken loads of great photos of the library for our Instagram, so I figured I could use one of those. She was happy for me to do this, as long as it was licensed for non-commercial use only, and that she got the credit if it is re-used. That seems fair enough, so: the following image was taken by Mandy Reeve, and is licensed under CC BY-NC 4.0:
If you are distributing some of your work, whether on the web or in physical format, and you're happy for people to re-use it, then consider applying a Creative Commons License to it. Do be careful though - once someone starts using your work under a CC License, you cannot change your mind and stop them. If you have produced something that you hope to make money from, it might be best not to licence any use.