what is dll files?

What is a DLL (Dynamic Link Library)?

definition dll files 1
A DLL is a library that contains code and data that can be used by more than one program at the same time. For example, in Windows operating systems, the Comdlg32 DLL performs common dialog box related functions. Therefore, each program can use the functionality that is contained in this DLL to implement an Open dialog box. This helps promote code reuse and efficient memory usage.

definition dll files 2

Stands for "Dynamic Link Library." A DLL (.dll) file contains a library of functions and other information that can be accessed by a Windows program. When a program is launched, links to the necessary .dll files are created. If a static link is created, the .dll files will be in use as long as the program is active. If a dynamic link is created, the .dll files will only be used when needed. Dynamic links help programs use resources, such as memory and hard drive space, more efficiently.
DLL files can also be used by more than one program. In fact, they can even be used by multiple programs at the same time. Some DLLs come with the Windows operating system while others are added when new programs are installed. You typically don't want to open a .dll file directly, since the program that uses it will automatically load it if needed. Though DLL filenames usally end in ".dll," they can also end in .exe, .drv, and .fon, just to make things more confusing.


definition dll files 3

Most programs require some form of dynamic memory management. This need
arises whenever there is a need to create data structures whose size or number is
not known at program build time. Search trees, symbol tables, and linked lists are
common examples of dynamic data structures where the program creates new instances at run time.
Windows provides flexible mechanisms for managing a program’s dynamic
memory. Windows also provides memory-mapped files to associate a process’s
address space directly with a file, allowing the OS to manage all data movement
between the file and memory so that the programmer never needs to deal with
, , , or the other file I/O functions. With
memory-mapped files, the program can maintain dynamic data structures
conveniently in permanent files, and memory-based algorithms can process file
data. What is more, memory mapping can significantly speed up file processing,
and it provides a mechanism for memory sharing between processes.
Dynamic link libraries (DLLs) are an essential special case of file mapping
and shared memory in which files (primarily read-only code files) are mapped into
the process address space for execution.
This chapter describes the Windows memory management and file mapping
functions, illustrates their use and performance advantages with several
examples, and describes both implicitly and explicitly linked DLLs.
Johnson M. Hart.Windows System Programming Fourth Edition. Addison-Wesley. page 131

Important topics
how to register dll files in Windows systems 10, 7,8, 8.1 and windows xp,vista?
how to unregister dll files in Windows xp, vista and windows 7, 8.1, 10, 32bit and 64bit?
how to fix dll errors for windows 7,8.1,10, xp, vista?
Dll error messages in windows xp,vista,8.1, 10,7.