The idea of journals/the journal network was initially conceived of in 1996 by a group of muggleborn friends who had seen how computers and the Internet have been revolutionizing the way muggles have been connecting and interacting across long distances. Eager to capitalize on this new idea, the friends pooled their talents (one worked in the Misuse of Muggle Artifacts, one in the Experimental Charms Committee, and one in the Floo Network Authority) to come up with the first prototype. A bit more fine tuning and the adding of ward functionality and they went on sale at Flourish and Blotts.
They were not an immediate success. More traditional witches and wizards preferred an OWL post or a nice Floo conversation over writing in a book, but slowly it began to catch on with those in and just out of Hogwarts. Predictably, they loved the portability and almost instantaneous means of communication. The fact that it could be easily smuggled into class was purely incidental, surely. As they grew in popularity, more features have been added including the ability to privately ward to specific people, ward notification, and the inclusion of pictures. The journals are sold in a variety of colors and styles to meet personal preference.
Entries posted in journals are viewable to everyone unless stated otherwise. Please note that this is a public network, readable by adult and student. Actions (and words) have consequences. If your character is in a position of power and says something controversial it could very well be reported on by the press. If your character mouths off to the wrong person in power, their life could become very difficult indeed, especially if they are shunned from fashionable social circles or even worse.
Strike-outs are readable and indicate text was marked out but is still able to be read. Bolded strike-outs, however, are not and represent text that has been scribbled out. It should always be assumed, unless stated otherwise, that if a private ward is not addressed to your character (s)he cannot "break into" the other characters' journal.
[Talk about Icons, if they are visible IC or are for OOC use only.]
Make sure to clarify the recipient(s) of a private ward are addressed to certain characters. Saying something like "close friends" is too vague (unless you specifically want to be vague and in that case your intent should probably be noted). Instead, list the names of those the private is addressed to. Established character groups (such as family members or school alumni), however, are acceptable. Warded text should be formatted as follows or in similer fashion:
[Private to Recipient's Name Here]
Alternatively, some players prefer putting wards behind a lj-cut. This is also acceptable.