The development system saves your work in several related files. The following shows the files from a program called TestProg:
The number of files saved will vary depending on what you have done, but there will always be three key files. One of these will have the extension .vb and another .sln and the third .exe.
The .sln (solution) file describes the overall project and the files making it up. If you have saved your work, and want to resume where you left off, you could double click the .sln file. (This is an alternative to starting the Development System, and clicking the open project button to find and start an old project).
The file form1.vb contains the definitions of the objects on the form and their property values. We will see later that it also contains the event handlers, the instructions the computer will execute when an event occurs.
Warning: since .vb files contain only ASCII text, do not use Word or some other word processor because you might accidently save the file in .doc or another word processing format.
There will also be a file with the extension .exe in the bin folder. That file is an executable program, ready to run on any computer that has the .NET runtime support software installed.
You can change your program by editing the form1.vb file with a text editor like Notepad. You should do that once or twice to be sure you understand the files the development system creates, but in normal practice, you would only make changes to a program using the development system.
If you write a program on one computer (say in a lab), and you want to move it to another computer, copy the project folder and all the files and sub-folders in it to some removable media like a floppy or Zip disk and move them to the other computer. (Be sure to close the files before you copy them)