The registry file in the Windows operating system is a big file or record where the Windows Operating system stocks up all the parameters it needs to run appropriately. Every time a program is accessed or called up, the registry file is read, and from there all the different parameters and components Windows are required to run properly are located loaded to get everything just the way you like it.
It comprises of 5 basic sections or Root Keys, which are then subdivided into a bulky number of sub-keys - a structure which looks a lot like the file folder storage on the hard drive, as presented in Windows Explorer.
It was created to merge all the numerous .ini files, which used to be dispersed all the way through the hard drive in the older Windows systems into one large storage area.
Because of the immense number of parameters it has to store and keep up, both for hardware and software, to give all the options and variables most users have turned out to be accustomed to, it has now grown into a huge file with structures and entries which are way too difficult for the regular Windows user to comprehend, let alone adjust or tweak. Even many savvy Windows users are apprehensive to touch the registry file.
Every time new hardware or a new program is added on the computer, a host of new entries are added to the registry, which is meticulous and compulsory for the proper operation of this program and to make available perfect combination into the Windows system.
When one un-installs a program from the computer, either in the course of the provided uninstall program or by means of the ‘add/remove programs’ option in the control panel, all the registry entries pertaining to that program are supposed to be removed. However this is usually not the case. Most programs leave many traces and entries behind after they have been un-installed.