When Windows 8 was made official, there were a lot of users who were not pleased with the way it looked, compared to its predecessor, Windows 7. Things did not improve when Windows 8.1 was launched, so developers started coming up with their own solutions - for instance, you can make your Windows 8.1 computer resemble Windows 7 by installing Aero 8.1 Theme.
You first need to patch your computer so as to be able to install third-party visual styles, then copy the actual theme files from the folder you downloaded to C:/Windows/Resources/Themes.
The next step is also the last one as you simply need to access the Personalisation area of Control Panel (simply select the Personalise function when you right-click your desktop).
You should see a section called Installed Themes and you can select the one you want from the list; if you are familiarized with Windows 7, you will surely recognize the themes’ names, as they are basically the ones included within Windows 7 (and they also contain the same wallpapers and sound schemes): Architecture, Characters, Landscapes, Nature, Scenes and United States.
At this point, you can start applying whichever theme you want, and stick with the one you like best. You will notice that some of the themes feature round corners, whereas other ones stay true to the Windows 8 style and display square ones.
The only difference between Aero 8.1 Theme and Windows 7 remains the fact that the windows borders are not transparent, so you might need to search for another tool if you are looking for this effect.
All in all, Aero 8.1 Theme does a good job in making Windows 8.1 look more like Windows 7 and less like Windows 8. Nonetheless, it is always advisable to create a restore point before toying with the settings of your OS, no matter which one it is, so you can safely return to your configuration if anything goes wrong.