The scientific name for an ear infection is otitis media. Otitis media is swelling or inflammation of the middle ear. The middle ear is usually filled with air although, sometimes, for example during a cold it gets filled with fluid or mucus. If this fluid gets infected with bacteria it can cause otitis media.

Anyone can get otitis media, however it is most common in young children, with more than 75% of episodes occurring in children under 10 years of age. An ear infection can be a source of discomfort and pain, in the case of otitis media with effusion (OME), it can lead to hearing difficulty or loss of hearing.

The information outlined above reflect current NHS Choices recommendations 

It is worth noting that not all earaches are caused by ear infections. If there are no symptoms other than the earache itself, it could be due to a different cause. For example, an earache can be caused by a build-up of uninfected mucus after a cold or a toothache.

There are three main types of ear infection:

Acute otitis media

Acute otitis media is the most common ear infection. Fluid is trapped behind the eardrum and parts of the middle ear are infected and swollen. The term "acute" refers to a short and painful episode.

Otitis media with effusion

Commonly referred to as glue ear, is caused by a build-up of fluid in the middle ear with no symptoms or signs of infection and usually follows an episode of acute otitis media.

Chronic otitis media

An ear infection that lasts a long time or comes and goes is called "chronic" otitis media. The inflammation or infection of the middle ear that persists or keeps coming back, and can cause long-term or permanent damage to the ear.