Traceability in .NET – 1 of 7

What is traceability?

From Wikipedia, http://en.wikipedia.org/wiki/Traceability :
Traceability is the ability to verify the history, location, or application of an item by means of documented recorded identification.
We define traceability in software tracking capabilities and implementation of software components to know exactly:
1 The date the component was done (so that we can reproduce the source code)
2 Details of the production (version frameworks, other components, compilation debug / release, other data) so as to have the ability to distinguish between different versions
Assume that we have already answered yes to step 1 (Do you use source control?) from http://www.joelonsoftware.com/articles/fog0000000043.html
Also (although we do not use;)) is good to study and Semantic Version http://semver.org/

Why we need traceability in software
Suppose we have a source code that you distribute one to several customers. Suppose we modify the code for version two. Some of his old clients make software upgrades – others not. If a customer reports a bug, how do we know which version of the source code had problems?