Tics are very common. It is estimated that up to 20 percent of children have some sort of simple tic during childhood and they are most prevalent between ages 7 and 9. Most tics affect the face and neck and consist of eye blinking, facial grimacing, shoulder shrugging, or neck twisting. They can also include throat clearing and sniffing. Most of these simple tics last a few months and then go away. They may be related to stress, but are also felt to be a part of normal brain development. Children who have tics cannot control them; they are involuntary movements. Children should not be punished or nagged about them. If there is a source of stress in the child's environment, parents should try to address it.
Tourette's syndrome is a more severe tic disorder in which the child has many motor and vocal tics (snorts, coughs, and other sounds or words). The motor tics in Tourette's can involve the arms or legs rather than just the face and neck. The tics are very frequent and often interfere with daily activities and schoolwork. Many children with Tourette's also have learning disabilities.
Since your son's tics have lasted for more than a year, and also started relatively early in life, I think it would be reasonable to have him evaluated by his physician, who can do a thorough neurological exam and also assess the frequency and severity of the tics. If there is concern about Tourette's syndrome, there are medications that can be used to control the tics.