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None - will show nothing and will also remove the element from its natural flow. Hidden - will hide the element displayed, but will not remove it from it's natural flow. Let's say you have an element and you use none, everything around it may start to look odd or should one say collapse - most likely not the look you were after. If it was hidden, the element will disappear but everything will stay in place.
visible- Default value. The element is visible hidden- The element is hide (but still takes up space) collapse- Only for table rows (<tr>), row groups (<tbody>), columns (<col>), column groups (<colgroup>). This value removes a row or column, but it does not affect the table layout. The space taken up by the row or column will be available for other content. If collapse is used on other elements, it renders as "hidden" initial- Sets this property to its default value. Read about initial inherit- Inherits this property from its parent element. Read about inherit