Magento Stages in life Cycle of Block

Blocks are the main part of the Magento so it has own life cycle .so how it works

1) Blocks are declared in layout XML or instantiated using PHP code
2) After instantiation the _construct() and _prepareLayout() methods are called
3) The controller's renderLayout() method calls toHtml(); all children are rendered
4) _beforeToHtml(), _toHtml() and _afterToHtml

Hope this will help you