This industry comprises establishments primarily engaged in providing expertise in the field of information technologies through one or more of the following activities: (1) writing, modifying, testing, and supporting software to meet the needs of a particular customer; (2) planning and designing computer systems that integrate computer hardware, software, and communication technologies; (3) on-site management and operation of clients' computer systems and/or data processing facilities; and (4) other professional and technical computer-related advice and services. Selling computer hardware or software products from retail-like locations and providing supporting services, such as customized assembly of personal computers,--are classified in Industry 443120, Computer and Software Stores; Wholesaling computer hardware or software products and providing supporting services, such as customized assembly of personal computers,--are classified in Industry 423430, Computer and Computer Peripheral Equipment and Software Merchant Wholesalers; Publishing packaged software--are classified in Industry 511210, Software Publishers; and Providing computer data processing services at their own facility for others--are classified in Industry 518210, Data Processing, Hosting, and Related Services.