Access points create new WiFi reception areas within a house. Stand-alone access points are suitable for a budget multi-room home WiFi network. Access points require Ethernet cables. WiFi range extender, also called a WiFi repeater, extends the WiFi network within a house. WiFi extenders have limitations - proximity to a WiFi router, no more than two extenders in a chain, possible instability, and dropouts of the WiFi connection. Prices are from $40.
Over-power adapters extend ethernet from the router to other rooms using power lines; no cables are required. Prices are from $60 for a pair.
Basic routers and modems in one are suitable for home or office internet. They provide a WiFi reception area within a house, typically within 15 metres radius on open space with up to 20 WiFi simultaneously connected devices. Prices are from $40.
WiFi and mesh networks with several access points are good for office or public WiFi installations, house-wide WiFi and where 100+ WiFi users are connected at once. Mesh WiFi systems usually provide additional management, monetization and security features. However, a pure wireless WiFi mesh may not be effective in big houses with concrete walls and ethernet cabling required. Prices are from $130 per device.
Network switches extend the number of Ethernet ports available from the router. PoE switches provide power to WiFi access points. Prices are from $30