" But many models can also describe themselves as actors. Some models have acquired the status of sex symbol, and a highly paid model is sometimes known as a "supermodel . " Supermodels are celebrities who may appear in advertisements endorsing products, and often parlay their fame into acting careers. "Runway modeling," also known as "catwalk modeling," is displaying fashion, and is generally performed by "fashion models. " "Glamour modeling" usually includes elements of nudity or eroticism, while "nude modeling" describes any kind of modeling that is performed without clothes. Art school modeling (usually figure drawing or sculpture) involves posing for students of art. Some models specialize in having a particular portion of their body photographed, usually for advertisement purposes; thus "leg models" advertise hosiery, "hand models" advertise nail polish or gloves, et cetera. Model Steam Boat For notable models, see supermodel and glamour photography. Some people who are better known for other accomplishments have also worked as professional models: 1908 Ford Model T advertisement Ford Model T used for giving tourist rides at Greenfield Village 1925 Ford “New Model� T Tudor Sedan The suspension components of a Ford Model T For the blues musician, see T-Model Ford. "

" The Standard Model of particle physics is a theory which describes the strong, weak, and electromagnetic fundamental forces, as well as the fundamental particles that make up all matter. Developed between 1970 and 1973, it is a quantum field theory, and consistent with both quantum mechanics and special relativity. To date, almost all experimental tests of the three forces described by the Standard Model have agreed with its predictions. However, the Standard Model is not a complete theory of fundamental interactions, primarily because it does not describe gravity. The Standard Model The Standard Model contains both fermionic and bosonic fundamental particles. Fermions are particles which possess half-integer spin and obey the Pauli exclusion principle, which states that no fermions can share the same quantum state. Bosons possess integer spin and do not obey the Pauli exclusion principle. Model Boat Motor Informally speaking, fermions are particles of matter and bosons are particles that transmit forces. For a detailed description of the differences between fermions and bosons, see the article on identical particles. "