Adware gets on your computer through downloads of just about every type. The most prevalent sources are free stuff such
as applications/ programs and browser add-ons. It was at one time rare to see adware on a Mac. Not any more even if you
only download from their store. Usually the suspect is the last thing you downloaded before the ads began to appear. It can also
appear after an update to an older program or add-on. Using P2Ps/ torrents are another source of adware when downloading free stuff
such as music, movies or cracked/ pirated applications.
If you are now not seeing ads then it is safe to assume the adware has been removed. But that doesn't mean it won't reappear
if you install the same add-ons, etc. that were removed during the reinstallation of your browser. If it does reappear check the
list of extensions for the browser. Often it is just a matter of removing an extension to kill the ads. Often in Macs it is as simple
as emptying the browser's cache or running CCleaner to remove whatever it removes in a Mac.
“Every atom in your body came from a star that exploded and the atoms in your left hand probably came from a different star than your right hand. It really is the most poetic thing I know about physics...you are all stardust.”― Lawrence M. Krauss
A 1792 U.S. penny, designed in part by Thomas Jefferson and George Washington, reads “Liberty Parent of Science & Industry.”