These IDs, in their various forms, are intended to make sure that the work of one scholar isn't mistaken for the work of another-- so that the right person is associated with a particular work or works (and so that citation can happen correctly, among other reasons). They are also being used as identifiers for some grants.
There are many names that are common in their countries of origin, such as Johnson in the United States, or Zhang in China. Even added first names and middle names or middle initials may not make one's personal name distinct from others. That is the reason behind the existence of these tools.
ArXiv is another resource that helps in this, though it is centered on physics and other sciences, and Mendeley and Zotero are becoming tools for this task, though it's not what they started out doing.
Registering in Web of Science allows you to create a ResearcherID, and to save and re-run searches. It also makes it easier to tag and send records, and allows you to use EndNote Basic through their site.Their form allows you to include other versions of your name, which may be important over the course of your career. Note: they are beginning to phase out the ResearcherID in favor of ORCID.
There are other products, such as Pivot, that try to identify specific scholars and help people find collaborators. Some of them are free, such as Mendeley and Researchgate. Mendeley also works as a citation manager.