An 8CK file is an application file used by the Texas Instruments TI-84 Plus C Silver Edition advanced math and science graphing calculators. It contains an application used by the calculator. 8CK files can be transferred from a computer to a TI-84 Plus C Silver Edition calculator using Texas Instruments TI Connect CE.
Apps can be used to extend the functionality of your graphing calculator. You can download a variety of apps that can create periodic tables, translate languages, simulate probabilities, and more. Apps are available from the Texas Instruments website.