Tennis elbow, also known as lateral epicondylitis, is an inflammation of the tendons on the outside of the elbow caused by repetitive motions like tennis, volleyball, or computer use. It causes pain on the outside of the elbow and weakness when grasping. Resting the elbow and avoiding aggravating activities for 2-3 weeks is the first treatment, along with icing, anti-inflammatory medication, and exercises to maintain flexibility and strength once healing begins.