CDC recommends that all people wear a face mask, especially those who are not fully vaccinated, full vaccinated people with weakened immune systems and to maximize protection from the Delta variant and prevent possibly spreading it to others, fully vaccinated people should wear a mask indoors in public if you are in an area of substantial or high transmission. To protect themselves from respiratory illnesses, including COVID-19. A face mask should be used by people who have COVID-19 and are showing symptoms. This is to protect others from the risk of getting infected and keeps people from touching their face. The use of face masks (KN95 and surgical) also is crucial for health workers and other people who are taking care of someone infected with COVID-19 in close settings (at home or in a health care facility).
Learn more on what the CDC says is important on masks and face coverings on their website.