The tangent function is a fundamental concept in trigonometry, representing the ratio of the length of the opposite side to the length of the adjacent side in a right triangle. It is commonly denoted as tan(θ), where θ is the angle. The tangent function is periodic, with a period of 180 degrees (or π radians), meaning it repeats its values every 180 degrees. In the unit circle, the tangent function can also be understood as the y-coordinate divided by the x-coordinate of a point on the circle. The function has vertical asymptotes where the cosine function equals zero, leading to undefined values. This behavior makes the tangent function unique among the primary trigonometric functions.