“Each basic style of alignment brings aesthetic qualities and potential hazards to the design of page or screen.”
Alignment is important to how we read paragraphs. Alignment styles include centered, perfect for a heading or a formal invitation; justified, a format often used in scientific journals; right aligned, a format normally reserved for languages read right to left; and left aligned, the most common format. Each of these can add to a website when used well or subtract from the aesthetic of a page if used poorly. Proper alignment in your text and designs will make them more visually appealing and will also make it easier for users to scan over a page.
What you want to think about is how suitable these alignments are for your text and how they sit in your design. For example, small amounts of text can work well in a centered alignment, though this will be more confusing and difficult to read on larger chunks of text. Similarly, with headings it might work well in your design to align them centrally, though this depends on the size of the text and where it is being placed. A centrally-aligned heading may not work well when it has a large chunk of text that is left-aligned immediately below.