Ground based observations of flares are reviewed to seek implications for a flare build-up on either a long or a short time scale. Plots of flare frequency and importance for certain individual centers of activity suggest a possible crescendo in flare occurrence days and hours before the development of large and significant flares. The X-ray records follow the same; pattern of apparent build-up. A possible dependence between successive major flares, as phases one and two of a single complex flare event, suggests that the time scale in which the total flare event takes place may show extreme variation.
Since all flares start as small features, there is a short term build-up in the optical records. The characteristics of this build up are not dear. The initial brightenings in a flare may or may not show a flash phase, and the rise to maximum may or may not be accompanied by filament activity. Flares rise to maximum Ha intensity at markedly different rates. Although most flares occur in centers of activity with well defined and often complex magnetic fields, certain large and relatively energetic flares have developed in centers of activity with apparently very simple circumstances.