Run Macro when cell changes

The code below does do what you want - sort of. Please try it and you will know what I mean. In essence, you shouldn't expect there to be an element "h1" in every one of your listed websites. In my trials there wasn't even a "Title". But the code loops over all the URLs in column A, writes what it find for a title in column B and ignores the error caused by the request for element "h1".

Option Explicit

Sub Get_Title_Header()

    ' Declaring and object as 'Object' instead of its proper type
    ' disables Intellisense dropdowns.
    ' Seasoned programmers, sometimes want "late binding" for reasons
    ' of compatibility, meaning they intend to use their program across
    ' different versions of Excel, which is exactly the reason why
    ' ready code copied from the Internet invariably use late binding.
    ' If your program is intended for wide distribution use early binding
    ' (proper object declaration) during programming and change to
    ' late binding (declare objects "As Object") only before publishing.
    ' Set the references mentioned below at Tools > References
    
    Dim IE As InternetExplorer  'Object = "Microsoft Internet Controls"
    Dim Doc As HtmlDocument     'Object = "Microsoft HTML Object Library"
    Dim sURL As String
    Dim Rng As Range
    Dim lastRow As Long
    Dim Rstart As Long, Rend As Long
    Dim Default As String
    Dim R As Long
    
    sURL = "Select the URL or contiguous URLs you wish to update," & vbCr & _
           "enter a cell or contiguous range address of such URLs," & vbCr & _
           "or confirm ""A1"" to update all."
    Default = "A1"
    lastRow = Sheet1.Cells(Sheet1.Rows.Count, "A").End(xlUp).Row
    Rstart = 2                          ' first row to process
    
    Do
        On Error Resume Next
        Set Rng = Application.InputBox(sURL, "Select URL to update", Default, Type:=8)
        If Err Then Exit Sub                ' user pressed Cancel
        
        If Not Application.Intersect(Rng, Sheet1.Cells(1, 1) _
                                    .Resize(lastRow - Rstart + 1, 2)) _
                                     Is Nothing Then Exit Do
            MsgBox "The range you specified isn't valid for the" & vbCr & _
                   "purpose of this macro. Please try again.", _
                   vbInformation, "Invalid range definition"
            Default = Rng.Address(0, 0)
    Loop
    
    With Rng
        If .Address(0, 0) = "A1" Then
            Rend = lastRow
        Else
            Rstart = Application.Max(.Row, Rstart)
            Rend = Application.Min(.Row + .Cells.Count - 1, lastRow)
        End If
    End With
    
    Set IE = CreateObject("InternetExplorer.Application")

    For R = Rstart To Rend
        sURL = Cells(R, "A").Value    ' the address is in C1
        Application.StatusBar = "Processing " & sURL

        IE.navigate sURL
        IE.Visible = False

        While IE.Busy
            DoEvents
        Wend

        ''HTML document
        Set Doc = IE.document
        Cells(R, 2).Value = Doc.Title

        On Error Resume Next
        Cells(R, 3).Value = Doc.GetElementsByTagName("h1")(0).innerText
    Next R

    IE.Quit
    Range("A:C").Columns.AutoFit
    Application.StatusBar = "All done"
End Sub

Edit 09 Apr 2020   ===================================

The code originally posted here was modified to ask the user to specify a cell or range of cell in columns A or B to be updated. If the macro is called from the worksheet (Developer tab > Macros -- [Select] > Run) the user can select a cell or range. Otherwise it can be entered.

If the user specifies "A1" the macro will update all items in the list, same as before. I have corrected referencing errors in the previous code and added progress information to show in the Status Bar (bottom left).