What is the junction that connects conduit to a structure called?
It's officially called a conduit body, but is sometimes called an LB by tradesmen.

It's known as an "LB", because the outlet (or inlet I guess) is on the back (ell back). There are also "LR" (ell right), "LL" (ell left), "T" (tee), "C" (cee), and "SLB" (service ell back) type conduit bodies available.



SLB not pictured.