How to check if you watch keeps accurate time

Curious if your watch is keeping good time? Could it be better?
We don’t have a timegrapher (machine that takes measurements of the accuracy of watches), so we head to our local watchmaker to have them test for us.

If you have the results, or are curious what levels of accuracy you can (should?) expect, take a look at these links:
The Real Reasons Watch Reviews Don’t Talk (Much) About Accuracy
Why You Should Own A Timegrapher (and how to use it) (however, this is good as a basic explanation on timing numbers as well, even if you don’t have intentions of ever purchasing one)

Some good threads on Watchuseek
How do watchmakers measure accuracy
How to read the result from the machine that checks the accuracy of a watch

And if you are ready to get deep into the details, a good read from Witschi (manufacturer of timers):
Test and Measurement Technology for Mechanical Watches