.2018 File

The 2018 file extension might be used for any data file created in year 2018, typically as some kind of backup to distinguish the data from previous years.

Such files are most frequently used by various tax preparation software, but might as well contain calendar, business or just be backup of some sort.

How to open:

Likely can be only opened or accessed in program that created the .2018 file in first place.

How to convert:

Sometimes export or conversion of .2018 files is possible, but no general info about 2018 conversion is available at this time.