Programming challenges are off-site challenges meant to offer programmers educational experiences while testing their abilities.
Challenges offer good insights into combinations, permutations, prime number generation, look-up tables, matching, regular expressions, etc. A well reviewed programming-challenge can be very educational.
Programming challenges can be found on sites such as:
and many more.
Note that this tag is not for questions about golfed/golfing code, as that is off-topic here.