Well, if you're talking Open Source, then the closest to "standard" is
LAMP:
Linux - optional, I supposed, since there are Windows versions of the other bits.
Apache web server
MySQL database
PHP, Perl, and/or Python
The P's are probably the more awkward: PHP is the standard, while many like Perl, though I much prefer Python. Since you're used to Delphi, the P could be made to stand for Pascal:
FreePascal, which (they say) "has excellent compatibility with TP 7.0 as well as with most versions of Delphi (classes, rtti, exceptions, ansistrings, widestrings, interfaces)".