When looking at buying climbing ropes, they are rated to a number of "UIAA falls".
What does that mean?
Although I am not a lab technician it is important to understand the dynamics at play in these tests. Below is the best example I have read on the subject.
For the full article please read below.
NOTE: Also included is the section on "impact force", which is a factor of the fall height, weight of the climber, amount of rope "out" at time of fall, and rope stretch. It is important to know as it can directly effect your safety.
Fall Test Overview
It means the rope is rated for X falls where the fall factor is 1.77 and the weight is 80kg. In layman's terms it's a pretty big fall with a pretty big guy, the sort of fall that if you took you most likely wouldn't want to climb again for the rest of the day! You may well never have such a big fall at all (in fact I'd hope you wouldn't!)
That said, the number is a rough guide and visual inspections should still take place regularly, especially on older rope that may have degraded over time. Equally because it's huge falls that the rope is rated for, don't feel that after x amount of (normal) falls you have to chuck it.
I'm sure I've seen some ropes with built in fall counters that work in terms of UIAA falls (measuring increments) if you feel that would be useful. In practice I wouldn't say it's necessary, but if you want one for added peace of mind then it might be something to consider.
Just to add to this answer, "fall factor" can be also thought of as this: