I wouldn’t recommend habitually using parentheses in essay writing. Newspaper articles, personal narratives, and other informal writing styles are the only types of papers that should have parentheses. So, it is best to know how to use them appropriately. Parentheses are used to add a piece of information that otherwise would cause the reader to misunderstand your point.
Example: My father took my two youngest brothers to the baseball game (my oldest brother was away at college).
Without the use of parentheses, the reader might think that my father didn’t want to take my oldest brother to the game. By adding the statement inside the parentheses, I made it clear that the oldest brother was out of town, and that’s why he didn’t go to the game. Making a new sentence to explain that my oldest brother was away at school wouldn’t be the best way to introduce that piece of information. Parentheses can also be used to expand on the details of a specific topic.
Example: My father took my brothers to the baseball game (Braves vs. Red Sox).
Sometimes seeing long names of popular organizations (i.e. Central Intelligence Agency) can be quite troubling for the reader of your essay. In an essay that will be using the name of the organization more than once, it is best to follow it with the common acronym associated with it (shown in parentheses).
Example: The Central Intelligence Agency (CIA) has been following Mr. Jones in a secret mission. Mr. Jones is unaware that the CIA has been tracking his location for the past few months.
Research papers require the use of citations to show from which sources your information has been gathered. Using parentheses to cite the references is appropriate. In APA style, cite the author’s last name followed by the page numbers. An example of this style can be found here.
eHow offers more helpful advice regarding the use of parentheses.