Mulch is any material applied to the surface of soil for protection or aesthetic improvement of the area covered.  There are two categories of mulch; organic and inorganic. 

Organic Mulch:

Organic mulch can be made of many substances which are naturally occurring.  Hardwood mulch and hardwood bark mulch are two of the most common.  However, pine needles, leaves, or even grass clippings are things around your yard you can use as mulch.  The key here is that organic mulches decompose over time.  Organic mulch can attract insects, mostly slugs and worms which is great for your soil. Unfortunately sometimes termites and other annoying pests get into it as well. Usually organic mulch should be replaced every couple of years.

Advantages to Organic Mulch:

Organic mulch provides nurturance to soil and plants mainly because it decomposes over time.  Organic mulch in most cases can be dyed and shredded to desired specifications.
They conserve water and protect from weed growth and aid in stopping soil erosion.  Organic mulch can also greatly improve the appearance of your landscape.

Disadvantages of Organic Mulch:

The main disadvantage is that organic mulch can attract termites and bugs.  As a result of it decomposing you will also need to re-apply every few years.

Inorganic Mulch:

There are many types of inorganic mulch on the market.  Inorganic mulch types include gravel, pebbles, plastic, and landscape fabrics.  These types of mulches do not attract pests and do not decompose, which can be beneficial in certain situations.  Some benefits of using inorganic mulch include conserving moisture, retaining moisture in root areas, controlling weed growth.

 Advantages of inorganic mulch:
Inorganic mulch does not decompose so it is a more permanent solution. This can save you time and money because you do not have to re-apply mulch every year.  Inorganic mulches do not attract pests which could be an advantage depending on the use.

Disadvantages to inorganic mulch:
They don’t decompose over time. Meaning if you want to change the look of your landscape, you will need to remove all the material from it.  There is also zero nutritional value to your plants and landscape beds.  In many cases inorganic mulch will get sun damaged and start to look worn over time.

 Most landscape supply companies would recommend organic mulch over inorganic mulch for a couple of reasons. Organic mulch decomposes over time providing nurturance to your plants and landscape.  It also makes it a less permanent decision and allows you to change the look of your landscape when you want to.