Introduction. The Saffman-Taylor Finger. Stationary Shapes of a Needle Crystal Growing from a Supercooled Liquid. Stationary Shapes of a Curved Flame Propagating in a Channel. Stability of Curved Fronts. Conclusion. References. Collected Papers. Planar Front Propagation. Dragging of a Liquid by a Moving Plate. Saffman-Taylor Finger. Dendrites. Directional Solidification. Raising Bubbles. Premixed Flames.