You can transmit your actual geographical position directly with every tweet. To do so, log into your Twitter account, click on the cog wheel symbol and select ‘Settings’. Here, activate the option ‘Add a location to my Tweets’ and confirm by clicking on ‘Save changes’. Do keep in mind that when using your home computer, the location is determined based on the IP, so the information could be rather vague.
Moreover, if you are tweeting via your smartphone, then the location is determined by the mobile GPS and is accurate. You can also see your exact location on Google Maps.