A gel pen is a writing instrument that uses a water-based gel ink, which provides a smooth and consistent flow. This type of ink allows for vibrant colors and a more controlled writing experience compared to traditional ballpoint pens. Gel pens are popular among students, artists, and professionals for their versatility and ease of use. These pens come in various tip sizes and colors, making them suitable for different tasks, from note-taking to artistic projects. Many gel pens also feature quick-drying ink, which helps prevent smudging, making them ideal for left-handed users. Popular brands include Pilot, Uni-ball, and Sakura.