`DateTime`

is a **point in time**, where as

`TimeSpan`

is a **duration**.

With this in mind, think of it!

The difference between two points in time is a duration.

E.g. the difference between yesterday noon (a point in time) and today noon (a point in time) is 24 hours (a duration).

The difference between two durations is a duration again.

E.g. the difference between 5 minutes (duration) and 3 minutes (duration) is 2 minutes (duration).

Now you can elaborate yourself what it means to add/subtract durations/points in time to/from durations/points in time.

Some combinations may not be meaningful, though.

Finally, the

`DateTime`

and `TimeSpan`

may not provide all possible operations from above.Cheers

Andi