Time is always something interesting to measure and to deal with, especially in embedded software that is, obviously, our main purpose here. The Arduino core includes several time functions that I'm going to talk about right now.
There is also a nice library that is smartly named SimpleTimer Library
and designed as a GNU LGPL 2.1 + library by Marcello Romani. This is a good library based on the
millis() core function which means the maximum resolution is 1 ms. This will be more than enough for 99 percent of your future projects. Marcello even made a special version of the library for this book, based on
The Arduino core library now also includes a native function that is able to have a resolution of 8 microseconds, which ...