We have already talked about nodes, content types, and fields. In Drupal, they often comprise the main content of a page. Very likely you will want to display extra information along the page. This can be accomplished using containers called blocks. For example, the main content of a page can be a news article and a block can be used to display a list of other articles written by the same author. You could also use a block to show a search box or copyright text. Let’s explore what Drupal blocks have to offer.
After understanding the difference between nodes and content types, let’s learn a new concept. Fields are Drupal's atomic data storage mechanism. They allow you to save discrete pieces of information which can be used for displaying, filtering, and sorting purposes.. Fields can be attached to nodes, users, taxonomy terms, blocks, and other Drupal entities. It is possible to share a field among bundles of the same entity. For example, you can share an image field among different content types (bundles) of the content (node) entity.