Tonsils are small glands which are an important part of the human immune method. The condition of infected tonsils is also often called tonsillitis. Persistent sore throat is the prime indication of some abnormality in the proper functioning of the tonsils. Viral infection or bacterial infection can be of the main reasons behind infected tonsils. Infected tonsils later on lead to swelling, inflammation & pus formation on the surface of the tonsils. These stages of infected tonsils depend on the type of tonsil infection.There are types of infected tonsils or tonsillitis, which are - acute tonsillitis & chronic tonsillitis. Acute tonsillitis is a sudden onslaught of irritation which regularly leads to inflamed tonsils. It usually affects children & lasts for about a week or so. While chronic tonsillitis is a resultant of recurrent tonsil infections. If neglected, such recurrent infections fail to reply to medical treatments. Chronic tonsillitis is primarily known to cause infected tonsils in adults.