Consent is a legally defined decision given by someone who is competent, who has been adequately informed (and has adequate understanding), and who is free from undue influence enabling them to make a voluntary decision. The person can provide consent themselves (provided they are competent). Otherwise someone else who is empowered by law can provide it (e.g. a parent in the case of children). A child who is not capable of giving consent alone can still be involved in the decision-making process with others who are able in law, to provide consent.
Assent is difficult to define and is used in diverse ways, e.g. compliance by a child as young as three, through to the active agreement of a young teenager etc. Assent is agreement given by a child / young person, or others who are not legally empowered to give consent. It is important to provide children / young people with information that matches their capacity when seeking assent.
Ensuring as far as possible that people who provide information or allow access to aspects of their lives as part of the research are given information about the purpose and uses of the research data. They need to know enough about it to be able to decide whether to participate (or for their parent/guardian/consultee to agree).
Participants should be informed about the risks and benefits inherent in the study and about their right to withdraw from the study. Typically this occurs via an information sheet.
It is important that you are clear about potential harms and do not overstate potential benefits. You need to explain how you intend to protect the participants from harm.
Consider if there is any possibility of either physical or psychological distress. If so you need to include details of how this will be managed (e.g. by providing details of free support services, for example victim support). If there are no direct benefits to the participant but the study may provide benefit in the future and enhance knowledge then this is the information you should provide to participants.
Also consider the limits of withdrawal. Typically studies should allow participants to withdraw at any time, however in practice this may not be possible. For instance, if data is collected anonymously with no identifying information it will be impossible to remove this afterwards or if you have begun your qualitative analysis or submitted you research for a course or for publication it will be very difficult to remove individual participant data at that point. Thus the actual limits of withdrawal should be made clear to participants.