An O-ring, also known as a packing, or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a disc-shaped cross-section, designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface.

The O-ring may be used in static applications or in dynamic applications where there is relative motion between the parts and the O-ring. Dynamic examples include rotating pump shafts and hydraulic cylinder pistons.

O-rings are one of the most common seals used in machine design because they are inexpensive, easy to make, reliable, and have simple mounting requirements. They can seal tens of megapascals (thousands of psi) of pressure.

The US patent for the O-ring was filed in 1937 by a then 72-year-old Danish-born machinist, Niels Christensen. He came to the USA in 1891 and soon after that patented an air brake system for streetcars (trams). Despite his legal efforts, his intellectual property rights were passed from company to company until they ended up at Westinghouse. During World War II, the US government commandeered the O-ring patent as a critical war-related item and gave the right to manufacture to other organizations. Christensen received a lump sum payment of US$75,000 for his efforts. Litigation resulted in a $100,000 payment to his heirs in 1971, 19 years after his death.

Park Bom (Korean: 박봄, Japanese: パク・ボム) (born March 24, 1984), is a South Korean idol singer. Born in Seoul, South Korea, she eventually moved to the United States where she learned English. She is currently a member and main vocalist of girl-group 2NE1 which is signed to YG Entertainment.

Starting in 2006, Park recorded with labelmates Big Bang, Lexy, Masta Wu and starred with Lee Hyori in her CF, "Anystar" as a co-actress. Later in 2008, she starred as the lead actress in Kim Ji Eun's music video, "Tell Me Once More". In 2009, she debuted with 2NE1 as the main vocalist.

Up till now, Park has released two solo singles, namely "You and I" and "Don't Cry". "You and I" reached number one on the Gaon Chart, the national music chart of Korea. The song also won "Best Digital Single" the Mnet Asian Music Awards in 2010.

Park Bom was born in Seoul, South Korea as a second daughter. In 6th grade, she left Korea by herself to study abroad in the United States. She graduated high school from Gould Academy in Bethel, ME and enrolled into Lesley University with a major in psychology. As a high school student, she fell in love with music through Mariah Carey. She would listen to Mariah Carey's songs during lunch and even forget to eat. She wanted to pursue it as a career but she did not obtain permission from her parents. However, with encouragement from her aunt, she secretly transferred to Berklee College of Music to pursue her music career.