Language (i.e., code) planning is the deliberate effort to control, expand, and utilize language. Cooper's definition of language planning is:
language planning refers to deliberate efforts to influence the behavior of others with respect to the acquisition, structure, or functional allocation of their codes
Language planning is important to a country for several reasons. The first is that planning is important to insure that a language corpus can function in contemporary society in terms of terminology, or vocabulary, to meet present needs, e.g., technological, or scientific needs. Thus, Cooper describes corpus planning as intervention to make sure a language has the needed terminology to function in necessary capacities.
The second reason is to establish the status of a language within a country and in relation to other countries in the world, for instance, it establishes whether a country will have one national language or two and which those two might be. As an example, South Africa effected status planning by determining that both Afrikaans and English would be official languages.
The third reason language planning is important to a country is that language planning determines how language or languages will be acquired, or taught, in the national educational systems. Acquisition planning comprises acquisition of national, second, and foreign languages.