To self-quarantine means to separate yourself from others because you have been exposed to someone with COVID-19 even though you, yourself, do not have symptoms. The goal of the self-quarantine is to prevent transmission.  Since people who become ill with COVID-19 can infect people immediately self-quarantine can prevent some infections from happening.

As the COVID-19 pandemic has evolved, variants have changed, immunity and vaccination have increased - the recommendation to quarantine after exposure to COVID-19 has been removed from February 2022, unless you develop symptoms.