defines the ability for a flex item to grow if necessary
dictates what amount of the available space inside the flex container the item should take up
a unitless measure that respresents a proportion or ratio
flex-grow value overrides the width of the flex-item
.item {
flex-grow: <number>; /* default 0 */
}
In the example above, the 2nd flex-item (green box) has its flex-grow set to 2 while the other flex-items have their flex-grow set to 1