The definite article is in French (as also in English) used for something well and precisely defined. It seems unnecessary to analyse the the exact use because there are so little differences that we recommend that you use them as you use them in English and things will go smoothly.
The definite articles (la, le) are in oppisition to the indefinite articles (un, une). They are used as the English definite article (the) and the indefinite article (a[n]).
