Application.GetOpenFileName

This method can be used to obtain a valid filename and its full path.
This should not be used but is still available for backwards compatibility.
To select a file you should use the Application.FileDialog - FilePicker method.

Excel

This method displays the Open dialog box but will not actually open the file.
This method will return a string value specifying the path and filename that was selected.

sFullPath = Application.GetOpenFileName(FileFilter, _ 
                           FilterIndex, _ 
                           Title, _ 
                           ButtonText, _ 
                           MultiSelect) 

FileFilter - This determines the types of files that will be displayed in the Files Of Type drop-down list. This argument consists of pairs of the file filter display text followed by the wildcard file filter specification. Each pair seperated by commas. The default is "User (*.*), *.*"
FilterIndex - This specifies which file filter is the default. Not required if there is only one filter provided.
Title -
ButtonText - This argument is not used in Excel for Windows.
MultiSelect - Determines if the user can select multiple files. If you allow multiple files to be selected you can use the IsArray() function to check if multiple files were selected.

All the arguments are optional.

sFullPath = Application.GetOpenFileName() 

When you want to filter the choice to specific file extensions you must use the following format: "description,*.extension"
The following line of code will display a dialog box allowing you to select an XML file.

sFullPath = Application.GetOpenFileName(FileFilter:="Excel Files (*.xlsx),*.xlsx", _ 
                          Title:="Please select an Excel file") 
If Len(sFullPath) = 0 Then 
   MsgBox("No file selected") 
End If 

Return Value = Variant
The value this function retuns must be assigned to a variant.

Sub DisplayFileOpen 
Dim sFilter As String 
Dim vaFile As Variant 

'build a filter list
'if you omit the space before the first comma excel will not display the pattern, (*.New)
      sFilter = "New Files (*New) ,*.new," & _ 
                "Old Files (*Old) ,*.old," _ 
                "All Files (*.*) ,*.*" 

'display the file open dialog putting the result in a variant
   vaFile = Application.GetOpenFileName(FileFilter:=sFilter, _ 
                                        FilterIndex:=1, _ 
                                        Title:="Open a New or an Old File", _ 
                                        MultiSelect:=False) 

'did you press Cancel?
   If vaFile <> False Then 
      MsgBox "You want to open " & vaFile 
   End If 
End Sub 

Word

Does not exist

PowerPoint

Does not exist