The phrase "essential element" refers to something that is absolutely necessary or extremely important for something else to function properly or be successful. It is a crucial part or ingredient that cannot be ignored or removed. Full definition
We give children responsibility and trust as essential elements of that caring relationship. (edutopia.org)
My critique group is the most essential element for editing in my case. (accrispin.blogspot.ru)
More businesses see smart watches, glasses and other digital gadgets as essential elements of long - range plans for improving worker wellness and productivity. (fortune.com)