Nexus Mod Manager
The Nexus Mod Manager (abbreviated to NMM) is a mod management tool provided by the Nexus sites. It cuts out the manual work of downloading, installing, and removing mods. It also allows the load order to be changed. It's currently in an open beta, and is at version 0.52.3. Because versions 0.50.0 and above are built with .NET Framework 4.5, a legacy version available to Windows XP users.
Packaging Mods for NMM
For a mod to be installed correctly by NMM, it needs all of the files inside of the distributed archive to be in the correct folder hierarchy. The top level folder represents the Data Files folder. Any plugin, master, and resource archive files are to be placed here. The next set of folders are all of the resource folders like meshes, textures, or icons. The resources that the mod needs should be placed within these folders.