Pain is an overall term that depicts any sort of unpleasant or awkward sensation in the body. Pain management is most important challenge in medical and dental field. Local anesthetics are backbone of pain control techniques. These represent safest and most effective method for managing pain associated with medical and dental treatment. Local anesthetics are the drugs which provides loss of sensation in circumscribed area without loss of consciousness. These drugs are in opposite to general anethesia. In order to induce anesthesia in a given area, a weak solution of anesthetic drug is applied topically to mucous membrane or injected hypodermically. It interferes with excitation process of the nerve membrane. Local anesthetics are reversible in nature with very less side effects and toxicity. Local anesthetics are widely used by the clinicians. Understanding the pharmacology and mechanism behind the action of these local anesthetics is of importance for more efficient clinical outcome. Potency, speed of onset, duration of action and safety of a specific drug in a given clinical situation depends upon properties of the local anesthetic. Other factors influencing anesthetic properties are dosage and vasoconstrictors concentration present in the solution. Local anesthetics travel many tissue barriers to reach their site of action. Local Anesthetics are toxic on many tissues but clinically apparent nerve damage is very rare. Local anesthetics induced toxicity after peripheral nerve block has a good prognosis overall. This article focuses on basic structure, function, mechanism of action and different techniques of local anesthesia.