As an author you own the rights to your work, which gives you exclusive control as to how your work is reproduced, distributed, or performed. However, during the publication process you will be asked to give away some or all of your exclusive rights.
Understanding the implications of retaining or giving away your rights can determine who can read your work, whether you can use it in your future work, and whether you can distribute it in class or to colleagues. If you transfer your full copyright, you no longer have control over how your work is used or distributed. Under copyright law, you can transfer some of your rights while retaining other important rights.