Composition is the art of arranging the elements within your frame into a pleasing image. It's up to you to determine what your subject is and to arrange the elements within the frame accordingly. Lines and shapes are important elements in composition. Lines draw your viewer into (or out of) the frame. They give direction. An S-curve (a curve that is shaped like an S) gently meanders through the frame, leading the viewer deeper into the frame, whereas a straight line is more direct. Curved lines are soft; straight lines have a more rigid feel.
Do you use a straight line or a diagonal line to reach the subject? Both will take the viewer there, but each has a different impact. Merging lines create a sense of distance, or vanishing point. Shapes are the result of a series of lines that come together to form a circle, square, triangle, and so on. Just like lines, the shape of your subject creates its own dynamic whether it's round, square, triangular, free-form, and so forth. Lines often lead to shapes, giving your images form. Patterns are repeating lines and shapes that make up an image.