"IfModule… in Apache 2 Fedora… Whats the use?

Question

#<IfModule mod_headers.c>
    Header unset Pragma
    FileETag None
    Header unset ETag
    ExpiresActive On
    <FilesMatch "\\.(ico|jpg..)$">
        etc
    </FilesMatch>
#</IfModule>

#<ifmodule mod_php4.c>
    php_value zlib.output_compression 16386
#</ifmodule>

Fellow Folks, Am I allowed to comment those IfModule stuff, as I am not planning to change for the coming whatever years and I am in no terms willing to change Apache for IIS or anything else in the universe.

In other words: whats the actual use of those ifModule stuff? Your enlightening suggestions or answers are much appreciated on this topic.

Answer 1

Those are conditional loads. If a specific Apache module is loaded, then allow that configuration block to take effect. If the modules are not loaded, they're not executed.