{% trans %}There are four main types of data. Content is the information (text, images, etc.) meant to be displayed to website visitors. Configuration is data that defines how the content is displayed; some configuration (such as field labels) may also be visible to site visitors. State is temporary data about the state of your site, such as the last time the system cron jobs ran. Session is a subset of State information, related to users' interactions with the site, such as site cookies and whether or not they are logged in.{% endtrans %}
{% trans %}A content entity (or more commonly, entity) is an item of content data, which can consist of text, HTML markup, images, attached files, and other data. Content entities are grouped into entity types, which have different purposes and are displayed in very different ways on the site. Most entity types are also divided into entity sub-types, which are divisions within an entity type to allow for smaller variations in how the entities are used and displayed. For example, the Content item entity type that stores page-level content is divided into content type sub-types; the Custom block entity type has custom block types; but the User entity type (for user profile information) does not have sub-types.{% endtrans %}
{% trans %}Within entity items, the data is stored in individual fields, each of which holds one type of data, such as formatted or plain text, images or other files, or dates. Fields can be added by an administrator on entity sub-types, so that all entity items of a given entity sub-type have the same collection of fields available, and they can be single-valued or multiple-valued. When you create or edit entity items, you are specifying the values for the fields on the entity item.{% endtrans %}
{% trans %}A reference field is a field that stores a relationship between an entity and one or more other entities, which may belong to the same or different entity type. For example, a Content reference field on a content type stores a relationship between one content item and one or more other content items.{% endtrans %}
{% trans %}The following field types are provided by the core system and core modules (many more are provided by contributed modules):{% endtrans %}
{% trans %}List fields associate pre-defined keys (or value codes) with labels that the user sees. For example, you might define a list field that shows the user the names of several locations, while behind the scenes a location code is stored in the database. Each list field type corresponds to one type of stored key. For example, a List (integer) field stores integers, while the List (text) field stores text strings. Once you have chosen the field type, the main setting for a list field is the Allowed values list, which associates the keys with the labels.{% endtrans %}
{% trans %}There are several types of text fields, with different characteristics. Text fields can be either plain or formatted: plain text fields do not contain HTML, while formatted fields can contain HTML and are processed through text filters (these are provided by the core Filter module; if you have that module enabled, see the related topic below on filters for more information). Text fields can also be regular-length (with a limit of 255 characters) or long (with a very large character limit), and long formatted text fields can include a summary attribute. All possible combinations of these characteristics exist as text field types; for example, Text (plain) and Text (formatted, long, with summary) are two examples of text field types. {% endtrans %}
{% trans %}A formatter is a way to display a field; most field types offer several types of formatters, and most formatters have settings that further define how the field is displayed. It is also possible to completely hide a field from display, and you have the option of showing or hiding the field's label when it is displayed.{% endtrans %}
{% trans %}A widget is a way to edit a field. Some field types, such as plain text single-line fields, have only one widget available (in this case, a single-line text input field). Other field types offer choices for the widget; for example, single-valued List fields can use a Select or Radio button widget for editing. Many widget types have settings that further define how the field can be edited.{% endtrans %}
{% trans %}Besides the field modules listed in the previous section, there are additional core modules that you can use to manage your content structure:{% endtrans %}
{% trans %}Depending on the core and contributed modules that you currently have installed on your site, the related topics below, and other topics listed on the main Help page, will help you with tasks related to content structure.{% endtrans %}