7.5. SupportPURPOSE
As attackers, Supports usually remain at the back of battle and cover their teammates so that theu they can get forward on the battlefield.
Also, Supports are highly effective against snipers as they can do covering fires fire that will affect Snipers' accuracy.
Eventually, Supports can supply their friends with ammunition.
As defenders, Supports can do suppression fires fire that can be extremely deadly.
7.4. SapperPURPOSE
As attackers, Sappers will destroy the enemy vehicles and deal damage-zone with their demolition weapons.
As defenders, Sappers will also plant mines to trap the enemy vehicles.
7.2. AssaultPURPOSE
As attackers, Assaults will mainly capture objectives - e.g. flags - and follow Recons to back them up for a strike
in the state of the art 
.
As defenders, Assaults will mainly
get take the enemy down.
6.4. Buy unlocks
While you are playing, get earn money for certain actions like capturing a flag, killing an enemy or destroying an enemy vehicle.
The squad leader
If one falls on the battlefield, they may choose to revive on their squad leader rather than reviving far far away on a regular flag. [i think respawn sounds better]
7.6. SniperPURPOSE
As attackers and defenders, Snipers will act as lone sharks and hide at the back of the battlefield.
They will usually assassinate the enemy players that are hard to kill a regular way.
...
SKILL
Snipers will have 20% of better accuracy with any weapons than the other classes.
In a couple of levels, there might be several flags that must be captured all together by the attackers before the next flag(s) become active. In these particular cases, all the flags which belong to the same "front-line" can be recaptured by the defending team until they all all of them belong to the defenders team.
If the attacking team manages to capture all the flags and complete the final objective before the end of the game, then they win the game. Otherwize Otherwise, the defending team wins.
I have seen a bug and/or I would like to give some feedback about stuff I don't like in the game.
First, you can use the so-named "F4 tool" in-game. To use it, simply press the F4 key in-game. The Then, you can write about your problem and/or send a screenshot with your report.
Normally, this tool is meant for bug-reports, but you can also you use it to send quick feedback about what you did not like in the game.
