Computer networks connect computers together through cables or phone lines. There are two main types - local area networks which connect computers in a small area like a home or classroom, and wide area networks which connect computers over larger distances. The internet is a global network of connected computers that began as a military communication system and later allowed commercial use through internet service providers. The world wide web allows people to share and view web pages containing text, images, video and sound through browsers, while search engines help users find information on the web. When using computers and networks, people should protect private data, avoid viruses, be careful sharing personal information online, and respect intellectual property laws.