OBSERVATIONSSince 2081 M I C has experienced electron cloud effects, which have Iimited the beam intensity. These include dynamic pressure rises -including pressure instabilities, tune shifts: electrons, a reduction of the stability threshold for bunches crossing the transition energy, and possibly slow emittance growth. We summarize the main observations in operation and dedicated experiments, as well as countermeasures including baking, NEG coated warm beam pipes, solenoids, bunch patterns, anti-grazing rings, pre-pumped cold beam pipes, and scrubbing. This article is a condensed version of Ref. El].Dynamic pressure rise from electron-impact desorption after an electron cloud has been formed was the first, and still is the most common electron cloud observation in RHIC [2,4,5]. It is also the operationally most relevant electron cloud effect in RHIC. This pressure rise is particularly pronounced at transition crossing when the ion bunches are short [6,73. In some cases the electron cloud switched off spontaneously, like in a second order phase transition [S], which can be explained if the both and electron and ion cloud is assumed 195.