System.IO.Compression Namespace

The classes in the System.IO.Compression namespace do not handle ZIP files. You can do some things with System.IO.Packaging, but it is not intuitive or easy. There's a nice, free third party library though, that will let you create, read, extract, and update ZIP files. DotNetZip.
http://DotNetZip.codeplex.com

It reads and writes regular ZIP files very easily. You can create or read ZIP files in WinForms apps, WPF apps, ASP.NET apps, mobile device apps, and more. It works with VB or C# or any .NET language. It's fully managed code. A single DLL. It supports Unicode, password protection, AES, streaming, ZIP64, file and archive comments, split/spanned archives, self-extracting archives, and more stuff. You can add or extract files by name. Or by wildcard. You can add or extract files based on file attributes, file size, or even file time. It has an easy-to-use eventing model. Full documentation in chm format. And the compression is very good. It's also very fast.

There's even a nifty little GUI tool that you can use to create zip files. It's a good replacement for WinZip - all based on the DotNetZip library.

Check it out. Free.

There's a GPL library for compression, implemented entirely in managed code.  I've found this library very easy to use in the past.

http://www.icsharpcode.net/OpenSource/SharpZipLib/

 

This is a method that will compress a directory of files using the ShellClass and the Shell32 api.

    Public Sub startCompression(ByVal stateInfo As Object)

      Dim strArgs As String = ""
      Dim strdest As String = ""

      '----- Check the file for a .zip extenstion.

      strdest += strDestinationFile
      If System.IO.Path.GetExtension(strdest).ToUpper.EndsWith(".ZIP") = False Then
        strdest += ".zip"
      End If

      If strdest.IndexOf(" ") <> -1 Then
        strdest = """" & strdest & """"
      End If

      '----- Binary Array representing a zip file header.

      Dim emptyZip As Byte() = New Byte() {80, 75, 5, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}

      '----- Write out the zip file

      Dim fs As FileStream = File.Create(Me.strDestinationFile)
      fs.Write(emptyZip, 0, emptyZip.Length)
      fs.Flush()
      fs.Close()
      fs = Nothing

      Dim sc As ShellClass = New ShellClass
      Dim src As Shell32.Folder = sc.NameSpace(Me.strSourceDir)
      Dim dst As Shell32.Folder = sc.NameSpace(Me.strDestinationFile)

      '----- Begining File Compression in System Controlled Thread
      dst.CopyHere(src, 20)
      

      '----- Sleep to allow the compression thread to begin execution

      System.Threading.Thread.CurrentThread.Sleep(5000) ' 5 seconds is usually more than enough
    End Sub