All information provided by http://wiki.teamfortress.com/wiki/Main_Page

The Medic is a Teutonic man of medicine. While he may have a tenuous adherence to medical ethics, he is nonetheless the primary healing class of the team. Although the Medic's Syringe Gun and Bonesaw aren't the greatest weapons for direct combat, he can typically still be found near the front lines, healing wounded teammates while trying to stay out of trouble.

When the Medic focuses his Medi Gun on a teammate, they will regain health points. Teammates who are already healthy will have their health buffed beyond the normal limit, up to 150%. Teammates who have not taken damage recently will be healed more rapidly, encouraging smart withdrawals when injured.

When healing, the Medic's unique ÜberCharge bar will gradually be filled, gaining charge faster if healing injured teammates. When the ÜberCharge bar is fully charged, the Medic's healing gun will begin to crackle with small jolts of electricity, indicating that he can now deploy a unique charge to benefit his patient and himself for eight seconds. A charge from the Medi Gun offers temporary invulnerability, a charge from the Kritzkrieg offers his patient guaranteed critical hits, a charge from the Quick-Fix offers rapid healing and immunity to knock back, and a charge from the Vaccinator offers enhanced damage resistance.

Although the Medic cannot heal himself, he is capable of slowly regenerating health over time; the longer a Medic stays out of combat and avoids taking damage, the faster his health will recover. An injured Medic will begin regenerating health at a rate of 3 health per second, scaling up over the following ten seconds to a maximum of 6 health per second. This base rate can be negatively affected by the Blutsauger and boosted with the Medieval Medic item set.

The Medic is voiced by Robin Atkin Downes[www.imdb.com]

Meet the Medic
Medic Update
Official Team Fortress Wiki - Medic