A heifer is a young female cow that has not yet given birth to a calf. Here are some key points about heifers:

• At birth, a female calf is often called a "heifer calf".
• A heifer in the final weeks of pregnancy is called a "springing heifer," and a heifer that is pregnant for the first time is known as a "bred heifer".
• Heifers typically give birth to their first calves at just under two years of age, usually bearing one calf at a time.
• Heifers are raised to breed, produce milk, and produce meat.
• Heifers do not have visible mammary glands, as the organs develop in response to pregnancy.
• Once a heifer has a calf, she automatically becomes a cow.

It is important to note that the term "cow" is often used to refer to any animal within the Bos genus of domestic and wild cattle, but specifically refers to adult female cattle that have had calves at some point in their lives.