## Force of mortality

Hi, I am working with some mortality data, In article, the author said that he used mortality data of mortality tables published in the Human mortality Database, in the paper he tries to fit some mortality data to some functions, he use the force of mortality.
Hi have seen these mortality tables, and these tables have the next columns:
Year

Year or range of years (for both period & cohort data)
Age

Age group for n-year interval from exact age x to just before exact age x+n, where n=1, 4, 5, or ∞ (open age interval)
m(x)

Central death rate between ages x and x+n
q(x)

Probability of death between ages x and x+n
a(x)

Average length of survival between ages x and x+n for persons dying in the interval
l(x)

Number of survivors at exact age x, assuming l(0) = 100,000
d(x)

Number of deaths between ages x and x+n
L(x)

Number of person-years lived between ages x and x+n
T(x)

Number of person-years remaining after exact age x
e(x)

What is the force of mortality, or what is the relation between every one wirh the force of mortality??