In order to fully understand and grasp the meaning of the term juvenile rheumatoid arthritis (JRA), one needs to look into its componential words and see what each of them mean. The term juvenile refers to the state of being young, childish or infantile. Rheumatism describes any painful condition related to the motor system of the body. This pertains to joints, muscles, soft and connecting tissues. As discussed to this point, the prefix rheuma- originates from a Greek word “rheuma”  which pertains to the flowing of a river or stream. Arthritis on the other hand is a term concerned just with joint disorders. The term again originates from the Greeks. “Artho-” means joint and “-itis” means inflammation. A joint is where bones meet such as the shoulder joint, knee joint, hip joint and the small joints in the hands and feet. Joining the terms to fully comprehend the phrase juvenile rheumatoid arthritis, one can conclude that it is a joint disorder found in youth. Indeed, arthritis is not a disorder exclusive to the elderly population.
Children at the age of sixteen and below who experience joint disorders fall in the category of juvenile rheumatoid arthritis. Children can complain about aches in their joints which can be caused by multiple reasons. However, if the pain persists for six weeks  or more or there is swelling on or around the joints, the child might be suffering from JRA. Arthritis is a chronic condition and lasts a long time. It causes inflammation of one or more joints, sometimes retarding bone development and growth. Important questions that arise from the discussion so far are: 1) Why categorize juvenile arthritis as a disease separate from that experienced by the adults?, and 2) Why can the two not be considered the same and treated as such when it is joint disorder that is the core problem? To answer these questions, some major differences between adult and juvenile rheumatoid arthritis are provided as follows: 
Quick Facts and Statistics
The majority of the patients suffering from JRA outgrow the disease, a finding that is very rare in the adult forms of arthritis. Rheumatoid arthritis in adults is a single disease with different manifestations, while JRA has distinct subtypes and is much rarer than arthritis in adults. JRA patients, more often than not, have negative rheumatoid factor (RF) in blood while seventy to eighty percent of the adults with rheumatoid arthritis have positive rheumatoid factor in circulation. JRA interferes with proper growth of the bones while that is not the case in adult in whom bones have already fully grown and developed. Due to these and other age-related factors, juvenile arthritis is termed a separate disease and dealt with accordingly. There are three major subtypes of JRA which can be determined by following the pattern of the disease in its first six months, considering how many joints are involved and whether certain types of antibodies are present in the blood. These include the following. 
The oligoarticular and polyarticular types of JRA are found to be more common among girls than among boys. However, systemic JRA equally affects girls and boys. Approximately fifty percent of the children suffering from JRA have the oligoarticular type, thirty percent have polyarticular type, and twenty percent suffer from the systemic type. Some important statistics, (from the same source) about the prevalence of JRA are listed below. These statistics give an insight about the magnitude of the problem and the number of people suffering from it. 
One out of every 1000 children is affected by JRA worldwide.
Young girls are more susceptible to the disease than boys are.
The disease is more common among Caucasians than any other race.
It is one of the most common childhood diseases found in the U.S.
Approximately 294,000 children are affected by JRA in the U.S.
Ambulatory care visits for JRA and other pediatric arthritis conditions are on average 827,000 annually.