I read a sentence: They walked heel to toe and selected the first stone that was encountered.
I knew every word here, but I just didn't understand what does "walked heel to toe" mean? Is it just walk?
Wikihow describes walking heel to toe as follows:
Place the heel of your foot down first and roll your foot slowly and gently toward your toes onto the ground. As you walk, rotate your hips slightly to make your steps even more controlled. Walk on the outer edge of your shoes if possible.
(The first sentence is the most important part.)
The YouTube video Heel to Toe Walking that
whitecap referenced in his comment shows how this works.