Green and Gold are two methods of making publications available as open access. An open access publication is digital, on the internet and free to read and download. There will usually be a license attached to the item saying it is free to use and share as long as the author is attributed and it may also state that the use must be non-commercial.
Gold Open Access
This is where the author pays the publisher for the rights to make the published version available as open access. These charges can be very high and it means that the publisher is paid twice. Firstly, by subscriptions so that subscribers can access the article and then a second payment to release the article from behind the publisher’s paywall so that it can be read by everyone.
Green Open Access
This is where a version of the article generally known as the author’s final version is made available on an Open Access repository such as Arrow@dit. This version in publisher’s jargon is known as “the post print”. This means that the version has been through the peer review process and any requested changes have been made. In most cases, publishers will let you upload this version to an institutional repository. Sometime this is before the item is actually published so the article can start attracting citations straight away after the revisions have been made. However, some publishers are now imposing embargoes of 12 or 24 months before you can upload the article to the repository.
Publishers’ Policies
It is important to check the publisher’s policy to see what is permissible. 
If you upload to Arrow, the Library will always check the policy before publishing the item. The publisher’s policy can be checked by typing the journal title into the Sherpa Romeo website. If it is not there, check the journal’s home page for their open access policy.
However, remember that in most cases you cannot use the published version unless you have paid the charge for Gold Open Access.
Work Flow
It is important to incorporate uploading the author’s final version (post-print) into your workflow as this makes your work freely available on the internet and increasingly many institutions and funders are making it mandatory to do so. However, the advantages are both personal and institutional. For the individual, making the work available as open access enhances discoverability, means it will be read by a wider audience and ultimately this may help to grow citations. From the institutional point of view, Open Access showcases the output of the institution, maximises uptake, monitors usage and impact of the research output of the institution and collects and manages a permanent record of the research.
The Dublin Institute of Technology has an Official Publications Policy, which entitles and obliges DIT authors to upload their work to the repository where that is possible and in compliance with publisher’s policies. It should also be pointed out that the repository will allow you to publish your research in many formats and not just academic articles.