"Here's a tasty morsel for you, my dear"
Breeding begins by a male singing, forming a territory and trying to attract a female. If he is lucky, a female bird will choose him and join him on the territory. He then usually diminishes or stops singing.
The female builds the nest and it may take a day or several days. There may be a pause before the eggs are laid. The pair will mate, then the female lays 1 egg per day until the clutch is complete. Most songbirds lay 3-6 eggs. She usually lays the egg in the morning and does not stay near the nest the rest of the time. So if you see 1 or 2 eggs in a nest it does not mean it is abandoned, chances are the female will come back the next day and lay another egg until she has a complete clutch.
Then incubation begins. It is done mostly by the female and usually lasts about 12 to 14 days (12-18 days for Eastern Bluebirds). During this time the female is quiet and the male stays somewhat near and does not sing.
When the eggs hatch both parents become very active bringing food to the nest. They carry away from the nest fecal sacs, little white packages that are the droppings of the young. This keeps the nest clean. The young, called nestlings, stay in the nest for about 12-14 days (longer for birds thart nest in birdhouses, for Eastern Bluebirds it's 16-21 days). The young at first have very few feathers. Then they have "pin feathers", feathers enclosed in sheathes. By the time they are ready to leave, the feathers have broken out of the sheathes, the young are fully feathered, and they call loudly.
When the young "fledge", or leave the nest they are called "fledglings". At first they may not be able to fly that well and for the first few days stay in the vicinicy of the nest. They are still fed by the parents for another several weeks. The fledglings often stay scattered in trees and call constantly. So if you hear constant chirping and see adult birds carrying food to different bushes or trees, chances are they are feeding fledglings. During the fledgling phase the adults may start a new brood. The male may sing again, mate with the female, and she will start a new clutch of eggs. even while he is still feeding fledglings from the first brood. The fledglings will eventually learn to feed themselves and the parents stop feeding them. and so the whole thing starts over.