A law firm is a business entity formed by one or more lawyers to engage in the practice of law. The primary service provided by a law firm is to advise individual or corporate clients or other business entities about their legal rights and responsibilities and to represent their clients in civil or criminal cases, business transactions and other matters in which legal assistance is sought.
Most attorneys at law firms start as associates. After a number of years, which can vary greatly from firm to firm, they may be invited to join the ranks of partner or shareholder, depending on the firm's structure, with the right to part of the firm's annual profit.
The differences among law firms can be startling. Due to the double-digit growth and globalization of the 1980's and 1990's, American firms can top 1500 lawyers with offices or linkages in such exotic places as Bangkok and Shanghai. Most firms above 100 or so attorneys are engaged in many practice areas, so that one client may work with many lawyers in different departments and various cities that semi-independently fill different needs.
Firms of any size are usually either client driven or substantively oriented. In the former, they handle either all or most of the clients' needs on demand, from business start-ups through mergers, dissolutions, acquisitions and bankruptcies, purchase and sale of real estate, labor agreements and estate planning to perhaps even the same client's prenuptial agreements, wills, residence sales and divorces. Boutique firms specialize and often gain their clients through referrals from general practice and other specialty firms. Common examples of such specialization are litigators in different fields (including lawyers who handle only trials), labor arbitrators and criminal defense lawyers. Many other specialty firms exist in areas that you may not even imagine, such as education board representation, municipal bond work, and oil and gas rights.
Firm structure can also vary greatly. Generally, very large firms (over 100 attorneys) are departmentalized and it can be extremely difficult or even impossible for an associate to move among departments. Most firms, however, give students and young associates the opportunity to rotate through several departments before making a choice. Each department generally has a head or chairperson, and attorneys work in teams or separately under his or her direction. Particularly in the first couple years, the work you are assigned will probably be only a small slice of the total business of any case.
The clients of large firms are usually medium to large corporations and their executive boards and management, government offices and institutions. A smaller general practice firm will have a mix of predominantly smaller businesses and individuals as their client base.
Small firms typically hire clerks for year round employment because they need certain tasks done, which do not require full time professionals or support staff. You are generally paid hourly wages comparable to those of undergraduate positions and an educational program is not arranged for you. You may be the firm's only clerk and will likely need to suggest opportunities to attend client activities. The partners may let you know that, regardless of your performance, they can't afford to offer you a permanent position following graduation.
The Career Planning library contains several publications that profile firms in considerable detail. A law firm's website is also a great source of information on everything from what clients the firm represents to a list of their attorneys and staff.