It receives a delimiter and a list of strings, and joins the strings into a single string, such that they are separated by the delimiter.
Note that the delimiter is written inside quotes.
@list = ("programming", "course", "for", "bioinformatics");
$string = join ("::", @list);
# $string is now "programming::course::for::bioinformatics"
$name = "protein kinase C";
$mol_weight = "450 Kilodaltons";
$seq_length = "120 Kilobases";
$string = join ("\t", $name, $mol_weight, $seq_length);
# $string is now:
# "protein kinase C\t450 Kilodaltons\t120 Kilobases"