Your credit history is simply the period of time you have had
open lines of credit. Say you had five credit cards and you kept
them each for exactly one year and then closed each of them. You
would have five credit years of history but most scoring systems
would see that as one year of credit history. If you had one credit
card account for one year and another for the subsequent year and
so on for five years, you would also have five years of credit
history, but, again, scoring systems would still see that as (more
or less) one year of credit history. Now, if you had one credit
card for five years, then the scoring systems would definitely see
that as five yeas of credit history.
So, creditors and scoring systems look at how long you have
maintained each line of credit and the longer the better.