The line that separates the top and bottom numbers of a fraction is called a vinculum. Fractions are also commonly written out using a forward slash in place of a vinculum for convenience on computers.
A fraction is a number that is not whole. In other words, in decimal form, there will be some number after the decimal place. The top number of a fraction is called the numerator, while the bottom is called the denominator. Fractions can be multiplied by multiplying numerators with each other and denominators with each other, but can only be added if they have the same denominator.