A core principle of scholarly communication is identifying and differentiating individuals. Names can be difficult to use as identifiers-- two people can have the same name; someone might change their name during their lifetime- so many groups have created researcher identifier (ID) or research profiling systems. In these systems, you create a unique ID number and attach this ID to all of your research outputs (publications, data sets, etc.). This identifier stays the same throughout your career, even as you change jobs, gain degrees, change names, or move to other research areas.
Some of the most commonly-used identifiers in health and life sciences are listed here.