LCD is nothing but Lowest or Least Common Denominator
Here LCD of 12 and 18 means LCD of two fractions with denominators 12 and 18 respectively.
Therefore, LCM of 12 & 18 = 6 x 3 x 2 = 36
The lowest common denominator or least common denominator (LCD) is the least common multiple (LCM) of the denominators of a set of fractions.
