Jets are ubiquitous in the Universe and are seen from a large number of astrophysical objects including active galactic nuclei, gamma ray bursters, micro-quasars, proto-planetary nebulae, young stars and even brown dwarfs. In every case they seem to be accompanied by an accretion disk and, while the detailed physics may change, it has been suggested that the same basic mechanism is responsible for generating the jet. Although we do not understand what that mechanism is, or even if it is universal, it is thought to involve the centrifugal ejection of matter from the disk along magnetic field lines. For a number of reasons, in particular their proximity and the abundant range of diagnostics to determine their characteristics, jets from young stars and their associated outflows may offer us the best opportunity to discover how jets are generated and the nature of the link between outflows and their accretion disks. Recently it has become clear that jets may be fundamental to the star formation process in removing angular momentum from the surrounding protoplanetary disk thereby allowing accretion to proceed. Moreover, with the realization that planetary formation begins much earlier than previously thought, jets may also help forge planets by determining initial environmental characteristics. This seems to be particularly true within the so-called terrestrial planet forming zone. Here we review observations of jets from young stars which have greatly benefitted from new facilities such as ALMA, space observatories like Spitzer, Herschel and HST, and radio facilities like LOFAR and the VLA. Interferometers such as CHARA and GRAVITY are starting to make inroads into resolving how they are launched, and we can look forward to a bright future in our understanding of this phenomenon when JWST and the SKA come on stream. In addition, we examine the various magnetohydrodynamic models for how jets from young stars are thought to be generated and how observations may help us select between these various options.

喷气机在宇宙中无处不在，可以从大量天体物体中看到，包括活跃的银河核，伽马射线爆发，微类星体，原行星状星云，年轻的恒星，甚至还有褐色的矮星。在每种情况下，它们似乎都伴随着吸积盘，尽管详细的物理原理可能会发生变化，但已提出由相同的基本机制负责产生射流。尽管我们不了解该机制是什么，或者即使它是通用的，但仍认为该机制涉及沿磁场线从磁盘进行离心喷射。由于多种原因，尤其是它们的接近性以及用于确定其特性的大量诊断方法，来自年轻恒星的喷流及其相关的流出可能为我们提供最好的机会，以发现喷流的产生方式以及流出与其吸积盘之间联系的性质。近来，已经清楚的是，在从周围的原行星盘上消除角动量从而允许积聚继续进行的过程中，射流可能是恒星形成过程的基础。此外，由于认识到行星的形成要比以前认为的要早得多，喷气机还可以通过确定初始环境特征来帮助伪造行星。在所谓的地球行星形成区域内，这似乎尤其正确。在这里，我们回顾了来自年轻恒星的喷射观测，这些观测已从ALMA等新设施，Spitzer，Herschel和HST等太空观测站等新设施中受益匪浅，以及LOFAR和VLA等广播设施。CHARA和GRAVITY等干涉仪已开始介入解决发射方式的问题，当JWST和SKA投入生产时，我们对这一现象的理解将为我们带来光明的未来。另外，我们研究了各种磁流体动力学模型，以了解如何产生年轻恒星的射流，以及观测结果如何帮助我们在这些不同的选择之间进行选择。