A Type Library is a software file that describes software interfaces in an operating system, typically Windows. It also describes co-classes, and other resources in a Common Object Model server. A type library file created by Visual Basic will always have a .TLB extension. The .TLB file is required by a client to connect to a server.



A type library can be thought of as a binary version of an IDL (interface Definition Language) file. Visual basic creates a type library when you create a VB server object, thus eliminating the need for an IDL file. A C-like language used to define interfaces and co-classes for COM. Ole View is a COM utility that reverse-engineers a type library into a readable form of IDL. IDL is used to provide language-independence for COM interfaces so that identical interfaces defined in VB, C++, and Java look the same in IDL even though they look different in the language used for implementation.

Other Types of Type Library

There is also the type library in the system that is used to display the type or font on the screen and printed document. This type or font library is located in the systems registry. Every time a program calls upon the type library top to display the font, the type library looks up the registry to locate the type that has to be displayed. If the type is not present in the library the page displays the default of the closest matching font for that type.

So What Is The System Registry?

The operating system must have the knowledge as to where to find certain files when the programs call on them for some function. This information was initially stored in the information folder denoted as INF in earlier versions of Windows primarily 95 and 98 first edition. Microsoft introduced the registry in windows 98 Second Edition to speed things up while loading and locating programs. But this can also slow the system down drastically. This Registry is a database used to store settings and options for the 32 bit versions of Microsoft Windows including Windows ME and NT/2000. The Registry contains information and settings for all the hardware, software, users, and preferences of the PC. This registry is constantly growing and updating itself. There will come a time when it will need to be cleaned. This can be done with one of the free XP registry cleaner if you are using XP or any other Microsoft free registry cleaner.

The physical files that make up the registry are stored differently depending on your version of Windows; under Windows 95 & 98 it is contained in two hidden files in your Windows directory, called USER.DAT and SYSTEM.DAT, for Windows Me there is an additional CLASSES.DAT file, while under Windows NT/2000 the files are contained separately in the SystemRootSystem32Config directory. You cannot edit these files directly, you must use a tool commonly known as a registry cleaner to make any changes in the Registry. It is in fact, advisable never to fool around with the Registry unless you have a trusted registry windows cleaner such as the PC registry cleaner or the Eusing free Registry cleaner which are available on many download sites free.