Book excerpt: Microbes Are The Tiny Organisms, Which Are Hard To Be Seen With The Naked Eye. However, In Spite Of Their Minuteness, Their Role In Human Life Is Of Considerable Importance. They Are Of Different Sizes, Shapes And With Different Tasks Assigned By Nature. They Are Also Called Bacteria In General Parlance. Some Of Them Are Beneficial While Some Others Are Harmful For Man. Apart From The Bacteria Related Directly To Body, There Are Others Which Provide Delicious Nutrition To Man. For Instance, Curd And Cheese. Both These Products Are The Result Of The Functioning Of Bacteria.Likewise, Many A Sweet Is Prepared With The Help Of Bacteria. On The Contrary, There Are May Bacteria, Which Are Harmful For Man. These Disease Causing Bacteria Enter Human Body Through Water, In A Majority Of Cases, And Through Inhalation Or Some Other Means And Start Destroying Cells Of Their Concerned Area. Weak And Strong-Both Kinds Of Theirs Exist. Present Work Is A Valuable Treatise On This Subject And Covers A Wide Range Of Issues In A Lucid And Interesting Style. It Fulfils Maximum Needs Of An Enthusiast.