Raising annuals from seed is a rewarding undertaking. It's cheaper than
buying plants at the local nursery. And you will get to know the plant much
better.

You are in Control
Add to that the complete control you have over what plants to raise into maturity and seed will be a viable option. But it doesn't end here!
An added advantage is that the more unconventional species or color variations might be available as seed, but not as young plant. Growing from seed can be your ticket to a special or unconventional garden. When the idea of doing it from scratch is not really your choice, there are in between solutions like flower mats, seed mats and more
Most Annuals are easy to grow, but especially those with very small seeds like Snapdragons or Begonia's can be a challenge.
Would is be different - Extinction would be immanent
The reason Annuals grow relatively easy from seed is part of their survival mechanism. Since the whole population have to be replaced every spring, faulty seed would mean disaster or the end of a variety. Buy your seed packets late winter or early spring. Sow them in flats, pots or other containers (the seeds from our shop always have the directions printed on the back).
Good seed packets, seed mats and other planting materials can be found in our special shop
The choice to start them inside or outdoors depends heavily on your local conditions. As a rule of thumb, you don't want to have seedlings outside when there is still a change of frost.
Spring warms the soil so the plant can take up enough water, the strength of the sun increases and allows the production of the nutrients the plant needs. Some Annuals really grow quickly. Which is also part of their survival strategy. You can sow them right outside where they will very quickly sprout and grow.
Examples of these plants are:
Zinnias
Marigolds
Nasturtiums
These cultivars might require you to do some thinning at one point or another but is very easy indeed. Always consult the back of the package for the details because they can vary even within the same species
Growing your own Annuals from seed will allow you to save considerably
and will also make the whole endeavor more interesting.
Contrary to Perennials you will enjoy garden flowers and color from the first season on.
Related Readings:
Suggested gardening resource: Gardentopia