Authors of academic articles originally own the copyright to their work. When their article is published in a subscription journal, they usually sign a copyright transfer agreement, which transfers most of their rights to the publisher. This may prevent the author:
For example, PhD students who publish journal articles that they later wish to include in their dissertation may have lost the copyright to these articles and may not have the right to use them in their dissertation without the permission of the publisher.
In some European countries, such as France or Germany, there is a secondary publication right which allows researchers to make the full text of their article openly accessible in a non-profit repository after an embargo period if their research has been funded by public money. There is no such right in the Swiss copyright law, which makes it particularly necessary for authors to retain some of their rights if they want to be able to self-archive.
It is strongly recommended that you read the agreement before you sign it and to think about the rights you want to retain. To make things easier, you can use an author's addendum such as the SPARC addendum. For example, it may allow you to change the embargo period to suit your funder's requirements.
Researchers with a Swiss National Science Foundation grant (awarded after January 1st, 2023) should normally reserve the right to make their work freely available under a CC BY licence with immediate effect, in accordance with the plan S Rights Retention Strategy.
If you have not retained certain rights that you need, you can ask your publisher for permission.