Annuals live over one season. Petunia Summersun Hardy annuals withstand frost and can be sown in the ground in the spring; haft-hardy annuals are frost-sensitive and are therefore started off inside to then be planted outside once there is little risk of frost. These are often referred to as bedding plants.
Biennials are started as a seed one year and flowering the next. The main reason for growing annuals is their speed of growing and their intense color. As the early summer perennials bloom before midsummer, annuals usually flower during midsummer, just before the profusion of late-season perennials. If you want an practically instant garden, annuals is what you should look for. Annuals also work perfect as temporary cover as you make up your mind about more permanent plants. They are also used to fill in empty gaps between areas in gardens as trees and shrubs reach their full-grown size.
For the best look in your garden, as with perennials, use foliage of other plants to create a border of a framework behind annuals.