The entire plant doesn't die when its growing season is over. You may not see any evidence of a living plant above the soil, but its root system is still alive and ready to send up shoots when the growing conditions are favorable for the plant again.
annual
Wildflowers are perennials. They will rebloom every year unless something changes the environment.
Plants that come back each year are called perennials.
Carnations are perennials, but many people grow them as annuals.
If the plant is an herb than it is a perennial. Some only survive for two years but are still called this. Other woody plants such as bushes and trees live for years.
The plants are either self-sowing (dropping seeds) or perennials
If the size of the pot is adequate and does not restrict their root growth so much that the plant dies, potted perennials can be grown successfully from year to year.
There are a couple of vegetables that are perennials and will come back every year, but for the most part vegetables are annuals that need to be replanted every year.
When planting a perennial garden, choose flowers with different blooming times to ensure that your flower plot always has something in bloom at any given time. Irises are an excellent choice for a beginning or intermediate gardener because they are easy to maintain, have three distinct blooming patterns and come in a wide variety of color choices. Also, if you have an iris-heavy garden, you will need to separate the rhizomes or roots every few years to keep the plants from crowding. Fortunately, there will be an abundance of additional flowers that can be planted elsewhere or shared with friends.
They will keep coming back, year after year. The leaves die in the winter, but the bulb underground remains viable.
The type of flowers that bloom every year without replanting includes perennial flowers. Roses, Plumbago, and hibiscus flowers are all examples of those perennial flowers.
They were probably annuals. Annuals do not grow back, unless they reseed. If you want flowers that grow back, you need to plant perennials.