What is factor of safety? Why is this necessary? what are the disadvantages?

The factor of safty is a number >1 considered to increase the durability of the product over the needed load to avoid failure under a certain sudden load 

The disadvantage is only that it causes an increasment in the cost of product over the exact specs

Factor of Safety (FOS)={Material Strength)/{Design Load}Design load being the maximum load the part should ever see in service. It is essential as it gives an idea of load a structure could support. However the disadvantage lies on the direct proportionality of cost and FOS

Factor of safety is capacity of a system beyond its required specs. It is necessary for any fluctuation in the specs or for any unknown variable which has not been accounted for during design or for any miss sumptuous. It is kind of insurance policy and it's premium is paid in the for of extra cost of product

Factor of safety is a term describing the structural capacity of a system beyond the expected loads or actual loads. Essentially, how much stronger the system is than it usually needs to be for an intended load.

but there a disadvantage of it that is when you increase the factor of safety, you will increase the cost of the product .

additional strenght for  anon known situation