A retrograde planet is an optical illusion since no planet can be in this position. When we say a planet is retrograde, it appears to be moving backward in its orbit from our perspective on earth. Although all planets appear to be retrograde at some point, it's Mercury that seems to be in this state more often. Typically, Mercury goes retrograde about three to four times each year.
According to astrology, the planets closer to the sun yield more influence on our lives compared to the outer planets.