ORCID is free of charge and your iD can be used throughout your career. You do not need to be affiliated with an institution to register for ORCID.
Your iD is visible to everyone and is displayed on your ORCID record below your name. You control the visibility settings of your record and can change items from public to private at any time.
Given that hundreds of systems now use it, it is likely that you will be asked to provide your ORCID iD eventually while submitting a manuscript, applying for a grant, or setting up your institutional profile page.
The best part about ORCID is that your iD distinguishes you and ensures that your research output is correctly attributed to you! It easily connects you with your contributions and affiliations and improves your discoverability.