A child grows and changes each and every day. From the time that they enter this world at birth up through the time that they are an adult, a child is constantly reaching milestones that include every area of development. Even after they have entered adulthood, they still continue to learn new things and hit new milestones until the day that they die. These milestones vary by age and include different characteristics, development, and life activities. There have been many psychoanalytic theorists over the years that have broken down the stages in a child's life. Sigmund Freud defined the stages as psychosexual stages because they were based off of sexual motivation. Another theorist, Erik Erikson, took what Freud discovered and broke it down further. Contrary to what Freud said, Erikson believed that humans develop in psychosocial stages rather than psychosexual. In my experiences, Erikson's findings are more sound than Freud's.
Erikson's theory is broken down into eight psychosocial stages of development, the first being trust vs. mistrust. This stage occurs in the first year of life. This is the time a child develops a sense of trust when their parent/guardian is providing care and showing them affection. They rely on stability and consistency. A lack of this will lead to mistrust. A baby is helpless. They depend on others to help them with everything from feeding to bathing to changing their diapers. If a baby is left unattended and crying then the baby will overtime start mistrusting their parent/guardian. This mistrust than generalizes to all adults. This first stage of a child's development includes many major milestones. Around the age of 4 to 6 months humans tend to see a lot of change. One will start to hear a child purposefully laugh and babble. A baby's motor ability grows and they are able to have control of their head and arm movements and start to purposefully grasp and reach for things.