A "Stata Dataset" is one in the special Stata format. Stata datasets have the extension .dta. To open a Stata Dataset, either use the Open option in the File menu or, in the Command window, type the use command followed by the name of a Stata dataset.
If you only need some of the variables from a Stata Dataset, you can just read in those variables with this variant of the use command:
use age sex status using survey1
To save a Stata Dataset, either use the Save or Save as option in the File menu or, in the Command window, type the save command plus a filename. If it already exists, you will need to add the option, replace. You do not have to type the file extension. The extension will be .dta by default.
save survey2, replace
Note: To create a file that can be read by version 8 or 9 of Stata, use the saveold command.
If you are using Stata/SE and want to save the dataset for use in the smaller, Intercooled version of Stata, use the option intercooled on the save command:
save surveyl, intercooled
String variables must be less than 80 characters to be saved in Intercooled.