Annuals are a great way to spruce up your garden on a yearly basis. On the one hand, they can be a lot of work since you can't just plant once and enjoy them for years. On the other hand, however, annuals allow you to change your garden's "look" more easily, since you can add new things every year! Annuals are also great for planters and windowboxes, since you don't usually put perennials in small containers. Some annuals can act as perennials by reseeding themselves prolifically; they can even spread to new areas, so you might want to be careful with flowers that can reseed. Some annuals are actually "tender perennials"; in temperate areas, they are usually planted as annnuals, but when the climate is warm year-round they can live for more than one season.
Most annuals prefer full to partial sun unless otherwise noted. Plants are listed alphabetically by common name.