Carrizo Oil & Gas, Inc. (Carrizo) is an independent energy company engaged in the exploration, development, and production of natural gas and oil. The Company’s operations are principally focused in producing natural gas plays known as shale plays or resource plays. The Company’s primary core area is the Barnett Shale area in North Texas (Barnett Shale or Fort Worth Barnett Shale), with a focus on Southeast Tarrant County, Texas. Through its wholly-owned subsidiary, Carrizo (Marcellus) LLC, the Company is actively seeking to establish a core area in another emerging resource play, the Marcellus Shale play in Pennsylvania, New York, West Virginia, and Virginia. It also explore for, develop, and produce natural gas and oil from traditional geologic trends along the onshore Gulf Coast area in Texas, Louisiana and Alabama, primarily in the Miocene, Wilcox, Frio, and Vicksburg trends. The Company’s other interests include properties in the United Kingdom North Sea.