Composition basics are all about the 'rudimentary' techniques that photographers use to compose their pictures. Whether used alone, or in combination with one another, composition often makes the difference between 'good' photographs and 'great' ones.
Although they are often referred to as the various 'rules' of composition, (e.g. 'The Rule of Odds,' or 'The Rule of Thirds') it is really more accurate to think of them as 'guidelines.' Generally speaking, most photographers can benefit from being aware of these basics of composition even if they have no intention of using them, if only for the fact that understanding them can help a photographer to understand what the outcome of their photographs will be when they decide to break compositional rules.