LAN, MAN, and WAN are three types of computer networks. LAN connects devices within a small area like a home or office using switches. MAN covers a larger area than LAN, such as within a city, using higher speeds. WAN extends over the largest geographical areas, such as across cities, states, or countries, using technologies like telephone lines that are more expensive and have higher latency. Each network type increases in the area and distance it can connect devices but comes with challenges like higher costs, lower speeds, and reduced reliability over greater distances.