The result, of course, is that I gain a much better understanding of myself and why I reacted to the day as I did. I enjoy telling stories of my small world and audiences don't come much wider. The life of a writer tends to be solitary. You work in isolation and it may be months before you'll get a reaction. My online journal generates a reaction within hours and that's nice.
Privacy can be a problem.
Some diarists don't seem to care who reads, use their real names and probably censor a lot of their entries. Another journaller, Blue Raindrops, somewhat strangely, asks people who know her not to read the diary, and if they do so, not to talk about what they have read.