Open Access (OA) is free, unrestricted online access to scholarly articles and information for everyone. This means the articles you are searching for are not behind paywalls if they've been made Open Access.
Open Access articles are of the same high-quality as paid journal articles. They have been peer-reviewed, are published in reputable, scholarly journals, and are appropriate to use in assignment reference lists. It just means that the frustration of hitting a paywall won't happen. It is great to us Open Access articles when doing more advanced research, especially for things like literature reviews.
The below boxes will tell you have to find Open Access material online. If you want to find out more about Open Access, you can have a look at this Library Guide on the subject.
The Open Access BUtton is free and legal browser button for Chrome that searches a number of different sources to find an open version of the article you are trying to read. It sources articles using institutional and subject repositories and legal databases like unpaywall. It does not use information from legally dubious sources such as Sci-Hub, academia.edu, or researchgate.com. In the case that an article is unavailable the Open Access Button will ask the author to make a copy available in a repository or other appropriate venue. Source
You can search using the Chrome button if you're on the page of an article and you're wondering if there's an Open Access version available, or you can search using the Open Access Button's website https://openaccessbutton.org/.
Below is a .gif of how the Open Access Button works:
Unpaywall is a free service that locates open-access articles and presents papers that have been legally archived and are freely available as open access. Unpaywall is a database of almost 20 million freely available scholarly articles. If a paper is available, Unpaywall’s grey ‘lock’ icon turns green and ‘unlocks’.
How to install Unpaywall
Below is an axample of an article with the green "unlock" option from Unpaywall.
IADT Library's website has a detailed list of different types of Open Access Sources including directories, preprint archives, Irish repositories, and more: IADT Library Open Access collections
This is the most common way of locating open access materials. As shown in the example below there will often be two links, one to the freely-available PDF version in an open access repository and the other to the published version, access to which will be dependent on a subscription:
The following are specific open access search engines:
Find over 40m open access publications, open datasets and software from over 18,000 content providers.
Gives you access to millions of scholarly articles aggregated from over 600 Open Access repositories.
Access to millions of scholarly articles and other materials (e.g. theses) from more than 3,000 sources.
An online directory that indexes and provides access to high quality, open access, peer-reviewed journals.
A directory of academic peer-reviewed books from many publishers.
Provides access to academic open access repositories from around the world.
Promotes the development of open access by providing timely information about the growth and status of repositories throughout the world.