The hip flexor is a group of muscles located in the front of the hip that play a crucial role in lifting the knee and bending at the waist. The primary muscle in this group is the iliopsoas, which consists of the psoas major and iliacus muscles. These muscles are essential for activities such as walking, running, and climbing stairs. When the hip flexors are tight or weak, they can lead to discomfort and limited mobility. Stretching and strengthening exercises can help maintain their flexibility and strength, promoting better posture and reducing the risk of injury during physical activities.