As mentioned above, the idea of visualizing events on a monthly calendar is based on a modified Gantt chart
. This technique fits ideally to represent and scale various blocks' width onto the timeline, giving the informative whole view.
Each block on a grid corresponds with tasks, plans, reminders, meetups, and other kinds of events. The colors of these rectangles may vary. It depends on event categories, preset by the user in advance (e.g. Work, Family, Friends, etc.). Some blocks may cross several days, representing the duration of this particular event. The starting and ending points of it, as a rule, sticked to a timeline. Thus it's obvious – the wider the block, the more time this event requires.
The calendar timeline is a plot made of cells, laid behind event rectangles to easily differentiate what block relates to a concrete day. By default, a calendar is shown as a monthly grid, however, it could be a week, a year, or even an intraday timeline.