Use:
When something is going to take place in the near future. It concerns things that have been arranged (for example a date, a concert, or a birthday that is in your calendar). So you have already made arrangements or preparations for it.
Form:
- form of to be + ww + ing (' am singing' of 'are working')
Example:
'Tom is taking Karen out for dinner tonight.'
'We are visiting our grandparents next Saturday.'