Mouth ulcers, also known as canker sores, are painful sores that develop on the soft tissues inside the mouth, including the gums, tongue, and inner cheeks. They can appear as small, round, white or gray lesions surrounded by a red halo. The exact cause of mouth ulcers is often unclear, but they can be triggered by factors such as stress, injury, certain foods, or underlying health conditions. These ulcers can make eating, drinking, and speaking uncomfortable. While most mouth ulcers heal on their own within one to two weeks, over-the-counter treatments and home remedies can help alleviate pain and promote healing. If ulcers persist or recur frequently, it is advisable to consult a healthcare professional.