  Coronal loops interconnecting two active regions, called as interconnecting
loops (ILs), are prominent large-scale structures in the solar atmosphere. They
carry a significant amount of magnetic flux, therefore are considered to be an
important element of the solar dynamo process. Earlier observations show that
eruptions of ILs are an important source of CMEs. It is generally believed that
ILs are formed through magnetic reconnection in the high corona (>150-200"),
and several scenarios have been proposed to explain their brightening in soft
X-rays (SXRs). Yet, the detailed IL formation process has not been fully
explored and the associated energy release in the corona still remains
unresolved. Here we report the complete formation process of a set of ILs
connecting two nearby active regions, with successive observations by STEREO-A
on the far side of the Sun and SDO and Hinode on the Earth side. We conclude
that ILs are formed by gradual reconnection high in the corona, in line with
earlier postulations. In addition, we show evidence supporting that ILs become
brightened in SXRs and EUVs through heating at or close to the reconnection
site in the corona (i.e., through direct heating process of reconnection), a
process that has been largely overlooked in earlier studies on ILs
