The Windows System32 folder contains your Windows operating system's core system files. Most of these files are vital to the functioning of your computer. Microsoft strongly advices against modifying or deleting any of the contents within your System32 folder.
Your System32 folder is located at C:\WINDOWS\system32. A few of the files and subfolders within the System32 folder are hidden. To view the hidden files in subfolders located within your System32 folder you have to access your folder options, select "Show hidden files and folders," and deselect "Hide protected operating system files."
There are many subfolders within the System32 folder such as the "Config" subfolder which contains event logs and registry files; the "Restore" subfolder which is where your restore points are saved; and the "Drives" subfolder, among other subfolders, which contains your systems installed drives.
In addition to containing subfolders, many of your Windows system applications are also stored in your System32 folder. The DOS command prompt ("cmd.exe"), for instance, is located in the System32 folder; so is the Disk Defragmenter ("dfrg.exe"); the Event Viewer ("eventvwr.exe"); Windows Task Manager ("taskmgr.exe"); the Registry Editor ("regedt32.exe"); even the Freecell card game ("freecell.exe") is located in this folder.