There a number of ways you can connect to a printer to send a print job from devices such as a computer, phone or tablet.  
Type Description
USB USB 1.0 which stands for Universal Serial Bus was released in 1996 and was intended to replace the parallel port connection and used to connect peripherals to the computer (such as keyboards, mouse, joystick, disk drives, media player, cameras, etc.).  It operated at speeds of 1.5 Mbit/s to 12 Mbit/s.  USB 2.0 was released in April 2000 with a speed of 480 Mbit/s.  USB 3.0 was released 12 November 2008 with a speed of 5 Gbit/s.
Wirless

Wireless (Wifi) uses radio waves that enables devices to communicate wirelessly.  Using wifi usually requires being within close proximity to the device.  The wifi range is approximately 20 meters or 65 feet.  The FCC allowed the use of Wifi starting in 1985.
Bluetooth Bluetooth is another wireless technology that operates using short wavelength radio transmissions.  It was created in 1994.  It requires very close proximity between devices. 
Parallel The parallel port was the popular way of connecting your computer to a printer for a very long time.  It uses a special cable that goes between the computer and the printer to establish the connection.  It is far less popular now because of new technology such as USB, bluetooth and wireless.
Ethernet Ethernet connection uses a RJ-45 port on the back of the computer with a built-in network card or a USB RJ-45 adapter that connects to a print server that places the printer on the network where it could be assigned a network address and communicate with all other devices on the network.  This enables you to print to the printer without having a direct connection to it.
Mobile Print Apps Mobile print apps are a new way of printing that enable printing from mobile devices such as smartphones and tablets.  In order to work the printers must come with the built-in software that enables mobile printing and a specific app must be downloaded and setup on the mobile device.