What is 'Bread Improver'?

Bread Improver is a mix of various acids and enzymes that serve to strengthen the gluten in the flour and feed the yeast, both of which yield a better loaf. The idea is to give bread a similar texture and taste to sourdough-based loaves, without having to go through the laborious feeding process usually involved with that method.

For more information, look at this Wikipedia article.

I'm surprised to see these marketed at the home baker ... one of the reasons to be making your own bread is to avoid all the unnecessary junk commercial bread contains! Admittedly, some of them might be relatively natural things, but it's still definitely unnecessary.

There's a good description of improvers in this article on gluten development. The main point is that they generally facilitate gluten development, resulting in dough with a stronger texture with less effort.

I think the bread improver are not required when we make bread in small quantity and provided we get the same quality of flour every time but when we make bread in large quantity in machines then these bread improver help in achieving consistent quality. it gives the dough the strength to withstand the machine power and reduces the time consumed in production of the bread