Default Angular 6 (and earlier) doesn’t support Internet Explorer 11 (IE11) by default

It is actually something that was apparently planned.

In order to resolve this issue, just open polyfills.ts and uncomment the relevant section.

For me it was:

Internet Explorer and the Z-Index (or, how I wasted a whole 3 hours of my life)

Internet Explorer and the Z-Index (or, how I wasted a whole 3 hours of my life)

Conditional statement for IE6

<!--[if lt IE 7]>
  <link rel="stylesheet" type="text/css" media="screen" href="other.css" />
<![endif]-->

lt - means "less then" - will link another css only for browsers less then IE7

Backup auto complete URLs in Internet Explorer

To get to the auto complete data, you will need to open regedit. Drill down to this key:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\TypedURLS

Source