The pet system in Forsaken World allows you to train numerous pets around the world to be used in combat with you. Starting at level 10 in Freedom Harbor, you will be given a free starter pet by simply following the main quest line.
To gain a pet, you must first hatch it out of its stone. Simply right click on a pet stone in your inventory to begin hatching it. The longer a pet egg hatches for, the better the pet will be statistically. When a pet is done hatching, you can take the pet out of the hatch slot and summon it. To summon a pet, equip it by right clicking the hatched pet in your inventory, then click "call".
A pet will assist you in combat by attacking enemies, and even buffing you. You can heal your pet with special pet potions that can be purchased from the pet food dealer. Also, your pet will get hungry over time. You can feed your pet with food from the pet vendor as well.
By killing enemies with your pet summoned, you will gradually level your pet up, which will make it stronger - and larger also.
One of the professions available is also very useful for catching and using pets. The tamer occupation will become available as you level up, and will allow you to capture the souls of monsters you defeat. These souls will appear as blue transparent versions of the monster you kill, and be captured and used to fight for you.
The pet system in FW is invaluable to helping you overcome the numerous challenges that you will face so take advantage of it as early as possible.