Backtiming is when someone sends an attack at you and you see it early enough you can work out what speed its coming at (what its slowest units are) and then what time it will arrive back in the attackers village after attacking you, this is an important game aspect, and is used throughout, however when you only have 1 village, you need to get a friend or tribe mate to send the backtiming attack, unless you are willing to send an attack without rams, etc (for speed purposes).
How it’s used?
It is used so you can then time an attack (yourself or a friend) to attack the attackers village within a second of his troops arriving home so he doesn’t have time to get his troops out of the village between them arriving home and your attack landing, and as offensive troops are useless at defending and you will obliterate their army, disabling them from attacking you for the time being.
To work out speeds you can use your own troops to see the travel time for each troop type between villages then compare with the time to arrival of the attack, or alternatively you can use the attack planner (http://www.tribalwars.co.uk/redir.php?url=http%3A%2F%2Fwww.twstats.co.uk%2Fuk11%2Findex.php%3Fpage%3Dattack_planner) entering the village coordinates then trying with the different troop types etc. If you have a premium account, simply view the village on your map and click the ‘troop speed’ drop-down option.
When troops return from an attack the time they arrive back in their own village is always rounded to the nearest second, not milliseconds. E.g. If you calculated that their troops would arrive back at 19:26:30:456, they wouldn’t, they would arrive at 19:26:30:000. So you want to time your attack to arrive just after this time, e.g. at 19:26:30:250, or any time very shortly after.
Please note; backtiming can sometimes lead to HUGE troop losses on your part; as during the time your troops are travelling to your attackers village, they could stack their village with defensive troops and destroy youroffensive force, but this is a risk that has to be taken. Use this skill wisely.