Chapter 6: User Interfaces for Mobile Media 273 and annotating the object. These tasks are related to the ‘E’ phase, as they should also be doable while enjoying the content. The ratings can be automatic and based on use count, but the problem is that the value is a system-generated prediction, not a sub- jective one. Often the rating is presented on a scale from one to fi ve stars, where one is the minimum and fi ve is the maximum. The user should be able to rate a content object while browsing or enjoying. For example, mobile devices with a numeric keypad support fast manual rating, as the user can rate the object with a single key press. Even if context information, from the time of object creation and throughout its whole lifetime, has been saved as metadata automati- cally, it still does not contain the user’s own interpretation of the situ- ation. Therefore, the possibility for user-created free-form annotations is important, as they can be used as keywords. 6.5.5 Share Content A counterpart of getting is sharing, which relates to the need or desire to give or dispatch personal content to one or more people to facilitate communication or share experiences. With mobile devices capable of wireless communication, this relates to operations such as sending, publishing, and uploading. For other devices, this relates to presenting the object with the device and perhaps later transferring it to another device capable of electronic communication. Personal content may be sensitive and private in many ways, which means that unintentional sharing of this kind of content (by automa- tion, error, carelessness) should be prevented. There should be differ- ent privacy levels for content based on metadata by, for instance, applying user-defi ned keywords that make the content always private. Such content objects need to be shared only explicitly and to trusted parties. It is also important that the user can be certain that the system will not share their metadata to others (preserve privacy or maintain ano- nymity) unless they explicitly wish it to do so. Sending has a strong analogy to real-world sending; it requires that the sender knows the receiver – or at least their address (be it a phone number or an e-mail address) – in order to deliver the message. Fur- thermore, the sender must be sure that the receiver is capable of receiving what is being sent. Sending a message, such as an e-mail, an SMS, and an MMS, is communication between people that are not in the same location and at the same time. The message is composed of a header (sender and delivery information, like on an envelope) and body part that contains