One of the first steps in conducting a systematic review is to develop a protocol that explicitly states the review question, objectives, methods, search strategy, eligibility criteria and dissemination plans for the review.
Registering a protocol is best practice and will help to avoid other people duplicating your systematic review. If you intend to publish the review it is advisable to register the protocol as early as possible. You will find details of eligibility criteria and information on how to register on the web pages of individual registers such as PROSPERO.
Scoping reviews are not currently eligible for registration on PROSPERO. Information on how to develop and register or publish a scoping review protocol is available in Chapter 11 of the JBI Manual for Evidence Synthesis.
If you are conducting a review for an undergraduate or master's dissertation award you may be asked to provide a protocol as part of your coursework but it will not be necessary to register the protocol unless you intend to have the work published.