A nicely mulched flower bed or garden looks neat and well cared for.  Mulch does more than that, however.  It conserves water, retards weeds, and adds  organic matter to the bed.  It is an important component to a well maintained garden.

Forests have a layer of decaying leaves and other vegetation that slowly transforms into a rich layer of humus.  This fertilizes the trees and keeps them healthy.  When we make a garden bed, the first thing we do is remove this layer so we see dirt.

If we are experienced, we till the earth to a depth of six inches, then till in three inches of compost.  Then we plant our garden in this soil.  The mulch is important, though.
Mulch helps hold in water until the plants need it.  If you have ever turned over a log and found a damp spot, you understand what the mulch does.  This means you have to water less often.

The second thing mulch does is retard weed growth.  Since the mulch blocks the sun, the weeds that need light to germinate do not grow.  The weeds that do try to grow usually starve before they make it through the layer of mulch.
Finally, the mulch acts as fertilizer.  It is suggested that you put a three inch layer of mulch around your plants.  Over the course of a year, the lowest inch slowly decomposes, adding nutrients to the soil.  If you add an inch each year, you will have a self-sustaining system of fertilizer.
Mulch can be pine straw, pine shavings, chipped wood, or shredded paper.  Some cities mulch the tree branches and other materials they cut to clear the power lines.  They then place it in a location where residents can go and shovel a load into their vehicle.  Other places sell that material.  You can call your city hall and find out if it is available or not.
Adding an inch of mulch a year also renews the look of the mulch for a neat garden. The work involved in putting out the mulch is more than rewarded by the weed control, water retention, and fertilizing functions it provides.

For more information about mulch, check out this complete guide about mulch.