I love beetroot, that is  the taproot portion of the beet plant
I am not familiar with it.  What do you do with beetroot.
Most times it is grown for their edible taproots and their leaves 
do you cook it prior to eating it?
That depends on the use because Many beet products are made from other "Beta vulgaris" varieties
Are they bitter?
food colouring and as a medicinal plant. Many beet products are made from other "Beta vulgaris" varieties, particularly sugar beet.
Etymology.
"Beta" is the ancient Latin name for beets, possibly of Celtic origin, becoming "bete" in Old English around 1400. "Root" derives from the late Old English "rōt", itself from Old Norse "rót".
History.
From the Middle Ages, beetroot was used as a treatment for a variety of conditions, especially illnesses relating
Beetroot
The beetroot is the taproot portion of a beet plant, usually known in North America as the beet, and also known as the table beet, garden beet, sugar beet, red beet, or golden beet. It is one of several cultivated varieties of "Beta vulgaris" grown for their edible taproots and leaves (called beet greens); they have been classified as "B. vulgaris" subsp. "vulgaris" 'Conditiva' Group.
Besides being used as a food, beets have uses as a