What kinds of things are mutable in Latin Rite Catholic Liturgy?

I got this email excerpt from the Compendium of the Catechism of the Catholic Church emailed to me today. > 249. Is everything immutable in the liturgy? > > In the liturgy, particularly in that of the sacraments, there are unchangeable elements because they are of divine institution. The Church is the faithful guardian of them. There are also, however, elements subject to change which the Church has the power and on occasion also the duty to adapt to the cultures of diverse peoples. What are some examples of the "elements which are subject to change" and how have they done so over the years? Has this change increased or remained steady since Vatican II?