Million bells, Calibrachoa, trailing petunia (Calibrachoa).
Calibrachoas are compact, mounded plants which grow 3-9" tall on mostly trailing stems. These plants are prolific bloomers that produce hundreds of 1" wide flowers from spring to frost. This plant is a tender perennial which produces flowers that look like small petunias. Flower colors include shades of violet, blue, pink, red, magenta, yellow, bronze, and white.
If you want more information about this flower, just search the plant's Latin (botanical) name on Google: