Dynamic Link Libraries

• Dynamic Link Libraries (DLLs) are modules that are used by other programs. They are a combination of functions and other data that can be called by the programs and services that use them. According to Microsoft's Developer Network, a few advantages to using DLLs include less memory usage, modular applications, and shared code between different applications. Svchost.exe controls these DLLs by having the ability to run them for the programs that need them, as Windows is unable to execute DLLs directly.
  
  

Number

• Svchost.exe runs many different instances in the background. DLLs are grouped and use a common svchost.exe process for each group. Groups are typically defined by common functions, according to How to Geek. This allows Windows to avoid a complete crash should a DLL fail--only that process or service fails, and it usually be recovered quickly.
  
  

Location

• The file svchost.exe is always in the same folder in Windows. You'll find it in "C:\Windows\system32." This folder contains many files that run Windows and its services.
  
  

Registry Keys

• If you need to find svchost.exe in the Windows registry for repairs or just out of curiosity, you'll find it at the registry key "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost." Unless you have a very specific reason for finding this key, do not alter or delete it or you will probably need to reinstall Windows.
  
  

Infection

• Svchost.exe can sometimes be spoofed by viruses and trojans. It might look like the same process that shows up many times in the task manager, but this implementation of it can be a virus. Virus scans can identify this, and updating Windows may help as well, according to Computer Hope.