This is not an easily defined flower. There are hundreds of species within the genus of Viola. Many are known as pansies. Many are known as violas or Johnny-jump-ups. Many are in between. The main difference between these two major groups is that, although very closely related, pansies bloom with bigger flowers, and violas bloom with smaller, simpler and more abundant flowers.
Blue, purple, white and yellow are the most popular colors for viola. Formerly uncommon orange and rusty red have become more popular in the past many years. Colors may be monochromatic, or arranged in intricate patterns with another color or two. The abundant bisymmetrical flowers are only about an inch wide. Mature plants should stay less than six inches tall, and spread as wide.
Violas are technically short term perennials that are typically grown as cool season annuals here. They are unlikely to survive through the innately warm and arid weather of summer. If planted now, they slow down a bit through the coolest winter weather, and then resume for early spring. If planted later in winter to continue slightly later into spring, they last only until the weather gets too warm.