ExtendedLibrary, a Potentially Unwanted Program (PUP) running on Mac computers, may be installed without the user's knowledge. It does not offer valuable or entertaining features, and it only replaces the default homepage, new tab page, or the search engine of the Web browser. If you're experiencing random redirects to search sites and other unwanted behaviors on your Mac computer, your PC could be manipulated by a PUP like the one above. This type of software is often spread via adware bundles and bundles that make use of deceptive techniques to make them seem attractive or useful.
Even if you identify the intrusive app on your Mac, it may be difficult to remove it manually since it will try to preserve some of its components by hiding them in various directories. The best way to ensure that ExtendedLibrary's removal is fully done is to run an up-to-date Mac security application.
Do note that ExtendedLibrary is not a harmful piece of software, and its removal is not mandatory. However, it is the best thing to do considering the lack of redeemable features – ExtendedLibrary's sole purpose is to bring traffic to 3rd-party sites by promoting them in your browser. Needless to say, such software should be removed without hesitation.