A touted feature of Drupal 8 is the ability to provide inline editing. Inline editing is enabled by default with the standard installation profile through the Quick Edit module. The Quick Edit module allows for editing individual fields while viewing a piece of content and integrates with the Editor module for WYSIWYG editors!
Let's provide inline editing:
The Contextual links module provides privileged users with shortcut links to modify blocks or content. The contextual links are toggled by clicking Edit in the toolbar. The Edit link toggles the visibility of contextual links on the page. Previously, in Drupal 7, contextual links appeared as cogs when a specific region was hovered over.
The Quick Edit module builds on top of the contextual links features. It allows field formatters, which display field data, to describe how they will interact. By default Quick Edit sets this to a form. Clicking on an element will use JavaScript to load a form and save data via AJAX calls.