A style can govern the whole layout of your work e.g. margins, font, spacing, alignment etc. A particular style is often used by a discipline and publishers within it. Getting familiar with a style will serve you well for the future. Always check which style to use with your Lecturer/School.
Websites and books for some of the main styles are listed below:
Many departments adopt the Harvard style and may have their own variations of it. Follow your department’s guidelines as outlined in the Student Handbook, or in class. examples of versions of Harvard style: