A line in geometry is a straight one-dimensional figure that extends infinitely in both directions. It has no width or thickness. A line is usually represented with two points or by using an arrow on both ends to show it continues without end. Lines are fundamental in geometry and mathematics.

Lines and angles are fundamental concepts in geometry. A line is a straight path extending in both directions while angles are formed when two lines meet. Types of angles include acute right obtuse and reflex. Understanding lines and angles helps in solving geometric problems and forming basic geometric shapes.