figure*environment) floats. As a result, there is a constant push for a means of balancing columns at the end of a twocolumn document. Of course, the job can be done manually:
pagebreakinserted at the appropriate place on the last page can often produce the right effect, but this seldom appeals, and if the last page is made up of automatically-generated text (for example, bibliography or index) inserting the command will be difficult. The flushend package offers a solution to this problem. It’s a somewhat dangerous piece of macro code, which patches one of the most intricate parts of the LaTeX kernel without deploying any of the safeguards discussed in patching commands. The package only changes the behaviour at end document (its
flushendcommand is enabled by default), and one other command permits adjustment of the final balance; other packages in the bundle provide means for insertion of full width material in two-column documents. The balance package also patches the output routine (somewhat more carefully than flushend). The user should be aware that any of these packages are liable to become confused in the presence of floats: if problems arise, manual adjustment of the floats in the document is likely to be necessary. It is this difficulty (what’s required in any instance can’t really be expressed in current LaTeX) that led the author of multicol to suppress single-column-wide floats.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=balance