LCD of Rational Expressions

What is the definition of the Least Common Denominator (LCD)?

How do you find the LCD of two rational expressions?

What is the LCD of $$\frac{1}{x}$$ and $$\frac{1}{x^2}$$ ?

What is the LCD of $$\frac{3}{x-1}$$ and $$\frac{5}{x+2}$$ ?

What is the LCD of $$\frac{2}{x^2}$$ and $$\frac{3}{x^3}$$ ?

What is the LCD of $$\frac{4}{x^2-1}$$ and $$\frac{5}{x^2-4}$$ ?

What is the LCD of $$\frac{1}{x+3}$$ and $$\frac{2}{x-3}$$ ?

What is the LCD of $$\frac{1}{x^2-4}$$ and $$\frac{1}{x^2-1}$$ ?

What is the LCD of $$\frac{1}{x^2}$$ and $$\frac{1}{x^2-1}$$ ?

What is the LCD of $$\frac{1}{x^2-3x}$$ and $$\frac{1}{x^2-4}$$ ?