  3He-rich solar energetic particles (SEPs), showing up to a 10,000-fold
abundance enhancement of rare elements like 3He or ultra-heavy nuclei, have
been a puzzle for more than 50 years. One reason for the current lack of
understanding of 3He-rich SEPs is the difficulty resolving the source regions
of these commonly occurring events. Since their discovery, there has been
strong evidence that 3He-rich SEP production is associated with flares on the
Sun. Anomalous abundances of 3He-rich SEPs have been attributed to a unique
acceleration mechanism that must routinely operate at flare sites. Flares
associated with 3He-rich SEPs have been often observed in jet-like forms
indicating an acceleration in magnetic reconnection involving field lines open
to interplanetary space. Owing to a fleet of spacecraft around the Sun,
providing a greatly improved resolution of solar imaging observations, 3He-rich
SEP sources are now explored in unprecedented detail. This paper outlines the
current understanding of 3He-rich SEPs, mainly focusing on their solar sources.
