There are three degrees of comparison:

cuadro33
Positive	Comparative	Superlative
Pedro es interesante.	Más interesante que Luis.	El más interesante de ellos.
Pedro is interesting.	More interesting than Luis.	The most interesting of them.
Angel es alto.	Angel es menos alto que María	El menos alto de todos.
Angel is tall.	Angel is less tall than María.	The less tall of all.
Ellos son limpios.	Ellos son tan limpios como antes.	Muy limpios.
They are clean.	They are as clean as before.	Very clean.
La silla es nueva.	Igual de nueva que la mesa.	Nuevísima.
The chair is new.	As new as the table.	Indescribably new.

We can use the comparative with nouns too:

Tengo tantos coches como usted./I have as cars as you.
Tiene tantas puertas como antes./It has as doors as before.

Irregular comparisons:

cuadro34
Positive	Comparative	Superlative
bueno(a)	mejor	el/la mejor (buenísimo/a)
good	better	the best
malo(a)	peor	el/la peor (malísimo/a)
bad	worse	the worst
pequeño(a)	menor	el/la menor (pequeñísimo/a)
small	smaller	the smallest
grande	mayor	el/la mayor (grandísimo/a)
big	bigger	the biggest