  We study multi-boundary correlators in 2d Witten-Kontsevich topological
gravity. We present a proof of the loop equations obeyed by the correlators.
While the loop equations were derived a long time ago, our proof is fully
explicit in the presence of general couplings $t_k$. We clarify all the
details, in particular the treatment of the genus zero part of the one-boundary
correlator. The loop equations are verified by several new examples, including
the correlators of Jackiw-Teitelboim gravity in the genus expansion and the
exact correlators in the Airy case. We also discuss the free boson/fermion
representation of the correlators and compare it with the formulation of Marolf
and Maxfield and the string field theory of Ishibashi and Kawai. We find
similarities but also some differences.
