I'm familiar with what DLL is, but lately I've been reading about third-party DLLs. Could someone closely explain to me what actually does that stands for. What I've been reading so far didn't get me a clear picture of what it is?
For example, if I'm programming in C#, how can I call(use, do, assign, ...) them?
A third-party is an organisation that is not your, nor the client. Third party DLLs are libraries created by other organisation outside of yours.
You can use these third party DLLs by putting them into a folder in your solution and then creating a reference to it (Project-> Right Click-> Add Reference).
Once you have the DLL, that DLL will have a namespace. Add a "Using" statement at the top of your C# file with that namespace and you will be able to access the classes inside the DLL.
Expanding on the previous answer it is probably worth mentioning, that "dll's" from third-parties often come with documentation, providing information on how to use that specific API.
