Almost everybody understands what is meant by the term anesthesia, although it is difficult to define formally. The term was originally coined to describe the state of unconsciousness that occurred after administration of ether or chloroform.
General anesthesia is a reversible state of unconsciousness and insensibility to pain.
It can well be described as a reversible state of oblivion. Regional anesthesia is when an injection of local anesthetic is used to anesthetize specific nerves leading to regions of the body. Examples of this include an injection into the brachial plexus to render the arm numb, an injection into the cerebrospinal fluid to anesthetize the lower limbs, etc. Local anesthesia is used to describe an injection of local anesthetic around an area, without blocking specific nerve trunks. An example of this would be an injection in the skin to numb it before suturing up a cut.