Articles are generally used to refer to specific plural or singular nouns. Plural countable nouns and mass nouns (words which are used as general terms – e.g. animals, people, sadness) do not always require an article. There are no rules to clearly identify when to use an article and when not to; the meaning of the word demonstrates the need for an article.
Cows like to bask in the sun.
Cows is a mass noun; all the cows like to bask in the sun. Sun requires a definite article because there is only one sun.
The cows in the field like to bask in the sun.
Here, we’re talking about a specific group of cows.
All over the world, humans are searching for the happiness.
The article before happiness is not required because happiness is used as a mass noun.
All over the world, humans are searching for happiness.
All over the world, humans are searching for the happiness they believe they deserve.
Because happiness in this sentence is a specific kind of happiness – the kind they believe they deserve – the article is required before happiness.
Farmers would do well to arrange for extra the stores of cattle feed this winter.
Because extra is already modifying the mass noun stores, the article is not required before stores.