Pharyngitis and tonsillitis are infections in the throat that cause inflammation.
If the tonsils are primarily affected, it is called tonsillitis.
If the throat is primarily affected, it is called pharyngitis.
A child might even have inflammation and infection of both the tonsils and the throat. This would be called pharyngotonsillitis.
These infections are spread by close contact with other individuals. Bacterial infections are more common during the winter. Viral infections are more common in summer and fall.