CKEditor

With this plugin enabled the longtext input fields will get a WYSIWYG editor which allows for some additional markup options for your text.

Depending on the configuration the editor can be enriched with various text style markup options. Have a look at the CKEditor website for a full featured editor.

Images

Elgg also supports uploading images in the editor. You can upload images using a file dialog or just drag/drop or copy/paste the image into the editor.

Mentions

With the CKEditor plugin you also enable mention capabilities. By default you can mention:

Users: use @ to start autocompleting users
Groups: use ! to start autocompleting groups
Searchable content: use [ to start autocompleting content

When you select something from the autocomplete list a link to the selected user/group/content will be added to the content. Based on the mentioned users preference they will also be notified they have been mentioned.