Modern Co.

Most Android phones today have micro sd expansion. However if you have a phone without this and are running out of room you should consider getting a USB-OTG converter (pictured) most phones with android 4.x and android 5.x supprot it although you should still google your phone name and "Otg support." This converts the micro-usb charging port to a full usb port. You can use wired game controllers, Mice, Usb sticks, and even keyboards.