King's Counsel (postnominal KC), during the reign of a female sovereign known as Queen's Counsel (QC), are senior lawyers in various Commonwealth countries.
They are appointed by letters patent to be one of "His Majesty's Counsel learned in the law". They are not a separate type of lawyer. They are more than long serving lawyers, because their status is given by the Crown and recognised by the courts.
King's Counsel have the privilege of sitting within the Bar of court, and wear silk gowns of a special design (hence the informal title Silks). The special robes are the reason why becoming a KC is often called "taking silk".
In order to "take silk" a lawyer usually has to serve as a barrister or a Scottish advocate for at least 10 years. Recently solicitors have also been appointed King's Counsel.
A KC's status means they generally charge higher fees than ordinary barristers, and always have another barrister as an assistant. This assistant is called a "junior" even if the junior has been a lawyer longer than the "silk".