Consider the file below that contains four variables, make, mpg, weight, and price. The file looks like what is shown below (the variable names are indeed the first line of data.)
make,mpg,weight,price AMC Concord,22,2930,4099 AMC Pacer,17,3350,4749 AMC Spirit,22,2640,3799 Buick Century,20,3250,4816 Buick Electra,15,4080,7827
You can read this kind of file using the insheet command as shown below.
insheet using comma.txt
We can issue the list command to see if the data was read properly.
list make mpg weight price 1. AMC Concord 22 2930 4099 2. AMC Pacer 17 3350 4749 3. AMC Spirit 22 2640 3799 4. Buick Century 20 3250 4816 5. Buick Electra 15 4080 7827
As you can see, the insheet command was pretty smart. It got the variable names from the first row of the data. It looks at the first row and can get the variable names from the first row. It also examines the file and determines for itself whether the data are separated by commas or by tabs. The exact same command could read the same file but delimited with tabs (you can try reading http://stats.idre.ucla.edu/wp-content/uploads/2016/02/tab.txt for yourself). If you would like more information about reading data in Stata, see the Stata Learning Module on inputting raw data into Stata.
As an aside, you can actually read the raw data file comma.txt directly over the internet into Stata, using the following command:
insheet using http://www.ats.ucla.edu/stat/stata/faq/comma.txt