As the tongue is predominately made of muscle, a sore one may be the consequence of infection, inflammation, trauma, malignancy and other abnormal processes of the tissues. Glossitis is a common condition and is an inflammation of the tongue that also results in tongue swelling and discoloration. It is caused by irritants, infection or other disorders.
Other possible causes of a sore tongue could be:
Enlarged papillae are when one or more of your taste buds become tender or irritated. It usually manifests with a painful pump on the tongue.
Burning tongue syndrome is the evocative name for a syndrome suffered by some post-menopausal women.
Excessive smoking can aggravate your tongue and make it sore.
If you're feeling particularly stressed then it could be canker sores. These mouth ulcers on the tongue are very common and the majority of people will at some point in their life get them.
Accidentally biting your tongue or scorching it with hot food or drinks can result in a sore tongue, though this will disappear as the damage heals.
If you have lumps or bumps on your tongue that to not disappear after a maximum of two weeks then you should consult your local doctor or family practitioner as it may be oral cancer. Please do not be alarmed, the majority of sore tongues are caused by nothing as serious as cancer although please bear in my mind that a great number of oral cancers will not be painful in the initial stages. Do not assume the nonexistence of pain means everything is fine.
Finally, medical conditions, including diabetes and anemia, can have a sore tongue as a symptom.
Any concerns, visit your doctor.