How the dlls in an ASP.NET bin folder get updated?

We have some DLLs in the bin folder. We build the DLLs in separate solutions and output to different directories. Now, when I build the web site, the DLLs in its bin folder gets updated aut开发者_JAVA百科omatically with the latest version (from those dirs). Now I am wondering how does that work? I mean, how did the build know from where to pull the latest bits of my DLLs? That looks magic to me...

When the website is getting build, the dlls will be copied to the target directory from the referenced location. Please check if the CopyLocal is set to True or False for each reference.

When building the web site, you must be referencing the DLLs from the other folder.