We use the before nouns which describe a general type of thing rather than a specific example of that thing:
These are problems for students living away from the family.
We don't know the effects of such chemicals on the body.
The role of the student at university level varies greatly from country to country.
Most of our business is carried out over the telephone.
The is also used before abstract nouns which describe a situation, a quality, a process or a change. These words are often followed by of something.
There is a problem with the availability of clean water in some villages.
The distribution of income is uneven in most countries.
On the whole, the standard of living is better in urban areas.
Many residents complained about the frequency of bus services.
This advance was brought about by the development of antibiotics.
He made a number of recommendations for the improvement of staff training.
We use the development/imrovement, etc. of something to describe a general process of change, but developments/improvements, etc. in someting to describe specific changes:
We try to keep up-to-date with new developments in information technology.