Some species, like the Globe Candytuft (Iberis umbellata) are annuals, others are perennials or have evergreen foliage.
Here is a macro of a light purple iberis flower, those many little buds in the middle will open soon.
Globe Candytuft, Iberis umbellata is a small, bushy plant, not more than 30-40 cm (12-16 in) tall.
It blooms from early summer until frost with lovely purple, mauve, pink and white flowers. The purple and mauve Iberis combines beautifully with orange-yellow marigolds, pot marigolds, in flowerbeds and borders.
The white one is very pretty too, as you can see in the following macro photo.
Iberis flowers thrive in full sun to part shade but doesn't tolerate heat. They like well drained, moist soil, they do well in rock gardens as well.
See also the Iberis sempervirens which has evergreen foliage.