title: C# .NET DLL files and using them in a .NET Web Application
body: <p>I Inherited a C# web application project from previous developers and they left no documentation for me other than code comments, and it has been taking me some time figure out what they previously did.</p>
  
  <p>So I found the class files .cs files they are using in the project in our team services (TFS) source control and one of the changes I have to implement is in one of the class files. However I could not find any of these .cs files on the production server.</p>
  
  <p>I found out later what they did was create a Class Library DLL file and added it to the web application on production, and that is why I did not find the class files on production, they are in the DLL file.</p>
  
  <p>I see the instructions for creating a new Class Library DLL, it is straightforward. My question is once I make my changes to the class, can I just create a new DLL file and swap it into the project to replace the previous DLL?, and if there is an error swap it back? </p>
  
  <p>Or is there more work than that involved?</p>
  
  <p>The previous developers were not using a development server, and also the source control does not match the production application and cannot be linked to the production server, and it is going to take me a lot of work to make a development server, so for now I have to make the changes directly to the production site.</p>