The flex-wrap Property of CSS

The flex-wrap Property
The flex-wrap property specifies whether the flex items should wrap or not.
The examples below have 12 flex items, to better demonstrate the flex-wrap property.
The wrap value specifies that the flex items will wrap if necessary
 .flex-container {
  display: flex;
  flex-wrap: wrap;
} 
The nowrap value specifies that the flex items will not wrap (this is default)
 .flex-container {
  display: flex;
  flex-wrap: nowrap;
} 
The wrap-reverse value specifies that the flexible items will wrap if necessary, in reverse order
 .flex-container {
  display: flex; 
  flex-wrap: wrap-reverse;
} 
The flex-flow property is a shorthand property for setting both the flex-direction and flex-wrap properties
.flex-container {
  display: flex;
  flex-flow: row wrap;
}