The paper introduces a new jet shape called N-subjettiness to identify boosted hadronically-decaying objects such as electroweak bosons and top quarks. N-subjettiness is a measure of how well jet energy is aligned into subjets and is used to distinguish between jets from boosted objects and those from QCD processes. It is defined as the ratio of different jet shape variables, such as τ₂/τ₁ for two-prong objects and τ₃/τ₂ for three-prong objects. N-subjettiness is effective in tagging boosted objects and rejecting QCD jets with large invariant mass. Efficiency studies show that tagging efficiencies of 30% are achievable with fake rates of 1%. The method is also effective in identifying new heavy resonances that decay to pairs of boosted objects. N-subjettiness combines the advantages of jet shapes with the discriminating power of previous jet substructure algorithms. The paper discusses the application of N-subjettiness to new physics searches, showing that it can significantly improve the discovery potential for new heavy resonances. N-subjettiness is an inclusive jet shape that can be calculated without reference to a jet substructure algorithm, making it more amenable to theoretical calculations. The method is compared to other jet substructure techniques and is found to be effective in improving the sensitivity of searches for new physics.The paper introduces a new jet shape called N-subjettiness to identify boosted hadronically-decaying objects such as electroweak bosons and top quarks. N-subjettiness is a measure of how well jet energy is aligned into subjets and is used to distinguish between jets from boosted objects and those from QCD processes. It is defined as the ratio of different jet shape variables, such as τ₂/τ₁ for two-prong objects and τ₃/τ₂ for three-prong objects. N-subjettiness is effective in tagging boosted objects and rejecting QCD jets with large invariant mass. Efficiency studies show that tagging efficiencies of 30% are achievable with fake rates of 1%. The method is also effective in identifying new heavy resonances that decay to pairs of boosted objects. N-subjettiness combines the advantages of jet shapes with the discriminating power of previous jet substructure algorithms. The paper discusses the application of N-subjettiness to new physics searches, showing that it can significantly improve the discovery potential for new heavy resonances. N-subjettiness is an inclusive jet shape that can be calculated without reference to a jet substructure algorithm, making it more amenable to theoretical calculations. The method is compared to other jet substructure techniques and is found to be effective in improving the sensitivity of searches for new physics.