Do not confuse a research protocol with a research proposal. A proposal is meant to persuade your instructor, peers, or a grant-making committee, while a research protocol is meant to detail a study's methodology in straightforward fashion to satisfy an entity's human subjects requirements.
A research protocol clearly and plainly provides an overview of a proposed study in order to satisfy an organization's guidelines for protecting the safety of human subjects who might be impacted by the work. Research protocols are typically submitted to Institutional Review Boards (IRBs) within universities and research centers.
While different entities use different names, generally, research that will not deal with human subjects directly or stands to have little effect on them is considered exempt. Non-exempt research often includes clinical trials where study participants face more risk than they would otherwise encounter in daily life.
This will vary from organization to organization, but typically a research protocol focuses on the aim and objectives of a proposed study, the methods that will be used to carry it out, how participants will be accessed, any risks they might run, and how these risks will be mitigated.
A key part of most research protocols is the informed consent document. This is a document that prospective participants will read before taking part in research. It details the study for them, including potential risks and benefits, and asks for their "consent" to participate.
Once a research protocol is approved by your IRB, you will have a certain amount of time to conduct the research (usually 1 to 2 years) before reapplying for approval. As a researcher, you have the responsibility to report any "adverse effects" that occur as a result of the research to the IRB.