What condition is commonly characterized by joint inflammation and pain?

Arthritis is a condition that is primarily characterized by inflammation of the joints, which leads to pain, swelling, stiffness, and decreased range of motion. There are many types of arthritis, with osteoarthritis and rheumatoid arthritis being the most common. In osteoarthritis, the cartilage that cushions the joints deteriorates over time, leading to pain and inflammation. Rheumatoid arthritis, on the other hand, is an autoimmune disorder where the body's immune system attacks the joints, causing significant inflammation and pain.

The distinct feature of arthritis is its direct impact on the joints, making it one of the most well-known inflammatory conditions. Symptoms vary in severity and may come and go, with flares of increased symptoms often occurring in response to stress on the body or changes in weather.

In contrast, fibromyalgia is characterized mainly by widespread muscle pain and fatigue rather than joint inflammation. Osteoporosis involves the weakening of bones without a direct correlation to joint inflammation or pain. A muscle strain, while it can be painful, specifically refers to injury to muscle fibers or tendons rather than an inflammatory joint condition. Therefore, arthritis stands out as the correct answer due to its defining characteristic of joint inflammation and pain.