There’s an artificial difference, I think, between calendars and to-do lists. Each one can replace the other — regardless of whether you’re using a smartphone, tablet, laptop, desktop PC, or even pen and paper.

This is because pretty much every calendar entry is a task — such as going to a meeting, or a deadline you’ve noted for something you have to do, or even a birthday or anniversary.

And tasks are, or should be, linked to specific times or days. It’s not enough to say that you’ll write a report — you should decide when you’ll write it by. Nearly every task I have has a due date, even if these are sometimes aspirational only.

Because calendar entries and tasks overlap in so many ways, I use ToodleDo for both.

So how do I distinguish between a task that should be done today, but could wait until tomorrow, from a calendar entry such a doctor’s appointment? I use priorities for that. The top priority, which in ToodleDo is displayed first and is bold-faced, is for time-specific tasks, such as a 12:00 appointment. I always put the time as the first five characters in the task description, e.g., 12:00 Doctor’s appointment. As nothing else appears in the top priority tasks, I can easily see when I have free time on a specific date, just as I would in a calendar.

In the past, like many of you, I’ve used both a calendar and a to-do list and found it confusing and redundant to do so. And this was even the case when using personal information managers that would display both calendar entries and tasks on the same screen.