A paralegal is basically exactly as it sounds - "next to an attorney" or an assistant to an attorney. This position can also be known as legal assistant.
The paralegal profession is a necessity in any law office, as they contribute to the research, interviewing, organization, clerical, drafting and other major functions that are crucial to the success of any attorney or law office. The role of a paralegal is to basically perform everything an attorney does - with the exception of actual arguing in court.
An incredibly significant portion of paralegal duty will be spent doing legal research - a tedious and time consuming, but fascinating task. A paralegal will typically pour over volumes and volumes of legal history books and government rulings to help a case. In some instances, a freelance paralegal, independent paralegal or contract paralegal will be brought in for one case only to assist in the mounds of legal research that needs to be completed.
Paralegals are typically in charge of drafting all legal correspondence and documents as well - an important task, and the court system requires records of all interoffice and inter-client correspondence. They're also in charge of drafting a trial notebook - a timeline of notes and research that the attorney will utilize during the actual litigation.
In addition to research and correspondence, a certified paralegal will also probably be responsible for extensive note taking. When a client first approaches the law office, it is important for the paralegal legal to record everything - what the client said, how they acted, whose names they may have dropped. Meticulous attention to detail and supreme organization are a must - and the case usually depends on it.
Legal investigations and client and witness interviews are typically conducted by a paralegal as well. Since the attorney is typically tied up in court, it's the paralegals responsibility to get answers to the most important questions pertaining to a case. Paralegals must treat each task for each case as though they were the attorney - and as though their good reputation were on the line.