  Compact radio emission provides a reliable method for the detection of low
luminosity young stellar objects (YSOs), and is particularly useful for
detecting the earliest stages of protostellar evolution where the source itself
may still be heavily embedded in its natal dust envelope. For such Class 0 and
Class I objects the dominant radio emission mechanism is expected to be
free-free, however unlike massive YSOs the way in which this radio emission is
produced remains a subject of debate. As larger samples of radio YSOs become
available the relationship between the radio luminosity of the Class 0/I
population and their wider global properties is now being clarified.
Furthermore, the broader scientific applications of such samples are also
becoming increasingly apparent. These improved constraints on the nature of the
radio emission from YSOs are now contributing to our understanding of not only
the evolutionary physics of protostars themselves but also their wider impact
on their surroundings. Here we discuss the physics of the radio emission, the
emerging relationship between this emission and other properties of YSOs and
some of the applications for studies exploiting this emission.
