Some USB-to-serial port adapters and Arduino board (or its clones) with FTDI chips are not recognized by the operation system automatically.
For example when Arduino board is connected to the computer, menu Tools of the Arduino IDE has its Port menu item disabled – when the FTDI driver is not properly recognized.
This article shows how to install FTDI drivers.
Module NRF24L01+ by Nordic Semiconductor is an ultra low power 2Mbps RF transceiver IC for the 2.4GHz band. It communicates with its special protocol and designed to save battery lifetime when running on battery.
The module can be connected to another device (e.g. Arduino board) over Serial Peripheral Interface (SPI)
Arduino board can be connected to LAN (Local Area network) with Ethernet-cards, designed either Arduino shields or connecting by wires. This allows to run network communication programs on Arduino, for instance a small Web-server.