Flare is a term used to describe those annoying little light patterns across a
photograph. It reduces
contrast and washes out colors. It leaves either the blackest part of the picture gray or else a line of ghostly rings. It's a problem encountered when the
photographer is shooting into the sun.
Flare is caused by non-image forming light getting into the lens. The easiest way to avoid this is to fit a hood to the lens to protect the front element from stray light or else to shade the lens with your hand. Change your position so the sun is outside of the viewfinder. Also keep the lens spotlessly clean.