维基百科说:

In the Microsoft .NET framework, an assembly is a partially compiled code library for use in deployment, versioning and security. There are two types: process assemblies (EXE) and library assemblies (DLL). A process assembly represents a process which will use classes defined in library assemblies. .NET assemblies contain code in CIL, which is usually generated from a CLI language, and then compiled into machine language at runtime by the CLR just-in-time compiler. An assembly can consist of one or more files. Code files are called modules. An assembly can contain more than one code module and since it is possible to use different languages to create code modules it is technically possible to use several different languages to create an assembly. Visual Studio however does not support using different languages in one assembly.

如果你真的浏览过，澄清你不理解的地方会有帮助

在Microsoft.Net中，程序集是代码版本安全、部署和可重用性的最小单元。

它包含:

- Assembly Identity
- Manifest
- Metadata
- MSIL Code
- Security Information
- Assembly Header

MSDN给出了一个很好的解释:

Assemblies are the building blocks of .NET Framework applications; they form the fundamental unit of deployment, version control, reuse, activation scoping, and security permissions. An assembly is a collection of types and resources that are built to work together and form a logical unit of functionality. An assembly provides the common language runtime with the information it needs to be aware of type implementations. To the runtime, a type does not exist outside the context of an assembly.

用更简单的术语来说:可以由. net运行时环境执行的(预编译的)代码块。. net程序由一个或多个程序集组成。

在.Net中，程序集可以是:

各种可管理部件的集合，其中包含类型(或 类)，资源(位图/图像/字符串/文件)，命名空间， 私有或公开编译的配置文件;部署到 本地或共享(GAC)文件夹;可被他人发现 项目/程序集和;可以进行版本控制。

程序集是.net应用程序的最小部署单元。 它可以是一个dll或exe。 主要有两种类型:

私人组装: dll或exe只是一个应用程序的唯一属性。它通常存储在应用程序根文件夹中 公共/共享组装: 它是一个可以同时被多个应用程序使用的dll。共享程序集存储在GAC中，即全局程序集缓存。

听起来困难吗?Naa…… GAC就是C:\Windows\Assembly文件夹，在这里您可以找到安装在PC上的所有软件的公共程序集/dll。

还有第三种也是最不为人知的装配类型:卫星装配。 附属程序集只包含静态对象，如图像和应用程序所需的其他非可执行文件。