A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
For questions about the Organic Groups module, not the Group module. It enables users to create and manage groups.
Use it for questions about importing/exporting Drupal code, settings, or content from a site to another.
The Services module provides a standardized solution for integrating external applications with Drupal. In Drupal 8 services are defined in YAML, they help to decouple reusable functionality.
Managing configurations across environments is part of the configuration management.
Use it for questions related to the Token module, or a similar form of token replacement system. Don't use it for authentication tokens.
Use it for questions about updating Drupal core and contributed modules.
Use it for questions about installing Drupal, modules, or themes.
Use it for questions about module and theme debugging (e.g. "How do I debug this situation?").
Use it for questions about Drupal's performance, how to measure, and improve it.
Use it for questions about configuring Drupal as multi-site, and/or using Drupal's multi-site feature.
Use it for questions about the module used by site developers to export elements of a site configuration to use them in another site.
Use it for questions about performing routine and other maintenance tasks in Drupal.
Use it for the module implementing a flexible flagging system, completely customizable by the administrator users: the Flag module.
Use it for questions related to site security, in particular those focused on protecting a Drupal site from unauthorized access.
The process of splitting the result of a query on different pages is called, in Drupal terminology, paging.
Use it for questions about the PHP application library dependency manager (Composer).
The module contains a set of APIs and tools to improve the developer experience.
Real-world geographic locations can be associated with Drupal entities.
Use it for questions relating to the Paragraphs module, not for text or body paragraphs.
The "Display Suite" module allows to take full control over how the content is displayed, using a drag and drop interface.
Use it for the user authentication/authorization on Drupal core or third-party modules.
Use it for questions about the configuration file used from the Apache server, the .htaccess file.
Use it for questions about integrating Drupal with the services provided by a social network like Facebook or LinkedIn.
Use it for the management of changes to documents and other information stored as computer files.
The tags placed in the <head> element to provide meta information about the document are called meta-tags.
Use it for the web mapping service application and technology provided by Google.
In a Drupal theme, the places where blocks can be put are called regions.
Use it for questions about the settings that can be retrieved with theme_get_setting(). Don't use it for generic settings.
In Drupal, it shows the hierarchy of the page that the user is currently viewing.
Use it for questions about the session system, which handles recognizing users from a session cookie.