The Name property describes the field content. The Name entered here will be displayed to an author when creating an entry. It's used to identify the chunk of content. This Name is also sanitised and used to generate the Field ID.
The Name field is limited to 50 alphanumeric characters or symbols. The words sys and entryTitle are reserved words and cannot be used.
The Field ID is used to identify the field within a content type through the API. The Field ID is automatically generated when creating a Name and sanitised for use as the Field ID.
Field ID's have to be unique within a content type. If you attempt to use a Name that is already in use then a number will be appended to the Field ID.
The Field ID is limited to 50 alphanumeric characters, symbols are not supported.
The Default value property sets the initial content for a field when an entry is first created. If no change is made by an author when editing the entry then the default value will be used.
e.g. Default location fields are set to London. So, if the default location isn't changed, that entry will be set to London.
The type of default value input will vary between field editors, not all field editors support default field.
Some fields support different Formats of data. By changing the data Format you are specifying the type of data that is stored and returned via the API.
Depending on the Format you specify you may be provided with different types of field editor for the field.
e.g. If you were to select the date field and change its Format from single to range you would see a set of editors that support date from and date to.
The Title field is used in listings, the Entry field editor and through the API to identify entries.
For a content type to be published it requires a single text field to be set as the Title.
The first text field added to the content type will be used as the Title field, if you decide you want to use another field for your Title field you can change it at a later date.
The read only property prevents an author from editing the contents of a field in the entry editor. This is especially useful if you are importing content from an external data source in to an entry that must not be changed by an author.