Windows is a OS by Microsoft. The first Windows OS was released in 1985 and was basically a theme for MSDOS. In 1995 Windows released their first true OS, Windows 95. This continued to the modern day, where now they compete with Apple for the "best OS".
Now, why do I care??i personally love old tech and computers and when my dad told me he had a copy of windows 2000, I jumped at the chance. There are less Windows OS's than Apple OS so that one might take awhile... Anyways, enjoy looking around!