"Microsoft has made many acquisitions for many reasons over its
history--122 to date, according to the list maintained at the
Wikipedia. Almost 100 of these have been consummated in the last
decade, as the company that triumphed in operating system and
office productivity software has sought (often unsuccessfully) to
achieve similar success in other domains. Other purchases have
demonstrated pragmatic 'build versus buy' decisions, serving to add
functionalities to products that needed them more quickly and
efficiently than in house efforts could achieve.
"In its earlier days, Microsoft was much more likely to mimic
the products of other companies rather than buy them, in part
reflecting its engineering-driven culture, and in part its hardball
approach to competition..."