Strength is a very important stat to have. It does not reflect a unit's physical power alone, at least in combat (where Attack Skill decides if the Strength does anything), but it's a very significant part of the picture.

Strength has a few uses:

• It is added to the base damage of most attacks in melee combat – the few that don't add Strength will say "Strength not added to damage" in their info sheet. The base damage of attacks is typically not zero, though it may sometimes be a negative number.
  • Two-handed melee attacks use 125% of the attacker's Strength.
• It is added to the base damage of a variety of ranged attacks, such as javelin throws and boulder tosses – some weapons (such as bows) only factor half or a third of the user's Strength into the damage done, however.
  • For some ranged weapons, Strength also determines the weapon's maximum range.
• It's the primary stat involved in Siege Strength, and it's also involved in Siege Defense.
• It's the primary stat for slipping from Entrapment.

Strength is not un-countered when dealing damage. Most targets will have some amount of Protection, which directly counters damage that doesn't ignore it, and both the attacker and the defender roll a DRN to settle the random variation in the damage dealt.

Generally, bigger beings are stronger. However, Strength is more of a measure of what they can do with their typical avenues of damage-dealing; their arms if they're humanoid, their claws or jaws (or tusks) if they're some sort of beast, et cetera. The trend between size and strength gets a bit weird past Size 6, too; this is most likely for game balance, as the downsides for increasing Size past 6 are far less than the downsides of increasing Size up to 6. Size 6 units can't pair up in the same square, after all, unless they're Gigantes.