The word "milestone" has the following definition in the Oxford English Dictionary [OED]:
"b. fig. A significant stage or event in the progress or development of a society, a career, an individual's physical and mental growth, etc.; a measure of progress or change. Cf. landmark n. 3."
Many geocachers use the number of caches found as a benchmark for this metric, and indeed, Groundspeak provides tracking of this in a tab of the statistics page of one's public profile. Curiously, Groundspeak (at least as far as I could find) does not provide a definition of "milestone" anywhere on their site or in their Help Center. There is a brief discussion of Milestones as regards Lab caches which can be found here (http://support.groundspeak.com/index.php?pg=kb.page&id=558
), but that has more to do with what they do and do not allow Lab caches to count for in their statistics generation schema.
Groundspeak counts the following finds as "Milestones:"
every hundred up to 1000
every 1000 up to 10,000
I did not chase it down higher than that, I had to look up Dixiegurl Suzanne's profile to get that far!
For folks to whom the numbers are of paramount importance, this may be the end of the discussion, but both Simon and I think that there are more well rounded ways to measure ones experience and performance as a geocacher. That being the case, we would offer the following metrics as additional measures of ones geocaching expertise; for us, any of these could be considered a milestone as well. Here's some ideas:
- helped a novice cacher in just about any way.
- found one of each type of cache
- hidden each type of cache
- collaborated on a cache hide with another cacher.
- completed the difficulty/terrain matrix/
- completed a map based challenge, like Delorme or ADC.
- cached in other states/countries/regions
- made a concerted effort to help travel bugs achieve the goals set out for them.
- completed a geotrail or power trail, or geoart series of caches.
- completed a streak of some sort.
- attended an event.
- attended a mega event.
- hosted an event.
- hosted a non-local event.
A quick look at Deepdish23's list of Maryland challenge caches may provide you with some other ideas.
For us, I guess the true measure of what makes you a better cacher, is what you have done to give back to the hobby. If any of your achievements push you towards that goal, whether by increasing your level of experience and well-roundedness (so that you can be a better resource to a newbie), or by demonstrating that idea directly, we'd call that a milestone.