Just to add to what the other monks have said on the subject, this is from the CGI.pm docs:

There will be some times when you want to produce the start and end tags yourself. In this case, you can use the form start_tag_name and end_tag_name, as in:

With a few exceptions (described below), start_tag_name and end_tag_name functions are not generated automatically when you use CGI. However, you can specify the tags you want to generate start/end functions for by putting an asterisk in front of their name, or, alternatively, requesting either "start_tag_name" or "end_tag_name" in the import list. Example:

In this example, the following functions are generated in addition to the standard ones:

start_table() (generates a <TABLE> tag)
end_table() (generates a </TABLE> tag)
start_ul() (generates a <UL> tag)
end_ul() (generates a </UL> tag)
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I haven't tested it with every HTML tag, mind... ;-)

Update: here's a link to the relevant part of the CGI.pm docs (as suggested by PodMaster).