Creating/extracting .tar.gz

Create an archive

tar zchf /var/db-dump/your-name-1-images.tgz -C / var/www/wiki.your-wiki-1/images/

Extract an archive

tar -xzf /var/db-dump/your-name-1-images.tgz -C / var/www/wiki.your-wiki-1/images/

Arguments used before

-c create an archive, one file that contains the target and everything below
-x extract

-f file
-z use gzip on the archive
-C change to this directory before any operation
-h follow symlinks; files/dirs in symlinks get archived too