This is a standard left-aligned paragraph. With left-to-right languages, this is the default alignment.
This is a right-aligned paragraph. This is the default for right-to-left languages, such as Arabic or Hebrew.
Here is justify-ied text--the text should be smoothly flowed between the left and right margins. Many browsers do not support full justification between both margins, and default to left justified.
This is centered text--it should be centered within the element, with ragged left and right margins. Note that the first line does not appear centered, due to the text-indent on that line.
This paragraph has no special alignment, but has a negative text-indent of -10%. As a result, the text is indented outside the browser border.