The bi-metallic £2 coin is the largest circulating coin denomination of the Pound Sterling. It was introduced in 1998 (earlier two pound coins were made of Nickel brass, were intended as commemorative, and did not circulate much). Being bi-metallic means that the coin comprises two separate components of differing alloys; the outer ring of the coins is made of Nickel-Brass (76% copper, 4% nickel, 20% zinc) and the inner circle is CuproNickel (75% copper, 25% nickel).
The Royal Mint maintains a "definitive" style of the £2 issued annually, as well as a large variety of one-year circulating commemorative types.
In 2017, the mint also started issuing some Non-Circulating Legal Tender (NCLT) £2 coins for collectors. These are included in the annual mint sets or are issued separately, but are not released into general circulation. Their themes celebrate important anniversaries or people, as well as iconic aspects of British culture and history. | 
