General Movement
A character's basic Movement is usually determined by his race and measured in meters per turn. Thus, a character with a movement speed of 8 can move 8 meters (tiles) per turn during combat.
Walking
Any creature's base walking speed is equal to its movement speed. Creatures of aquatic nature, like fish, do not have the ability to walk on land unless they explicitly mention in their description that they are capable of doing so.
Difficult terrain
Difficult terrains, such as ice or spiky ground, may hinder a creature's movement, in which case its base movement speed will be halved. This penalty also applies to all the other forms of movement below.
Long-distance travelling
A creature can travel approximately 8 kilometers per day per unit of movement speed. Meaning for example a creature with a movement speed of 6 can travel ~48 kilometers per day without tiring.
A creature can increase that amount to about 10 kilometers per day, but it will cause the creature to become exhausted and have halfed movement speed for the next 24 hours.
Climbing
A climbable surface can be traversed by any creature with at least two hands (or hand-like limbs like, for example, tentacles) at one-third of its current movement speed rounded down, but never less than 1. If a creature ends its movement on a wall, it is unable to use its hands for anything else.
Types of climbable surfaces
Climbable surfaces have three degrees of difficulty: easy, moderate, and challenging.
Easy
Easily climbable surfaces can be climbed by any creature mentioned above at their normal climbing rate.
Moderate
By default, moderately climbable surfaces can only be climbed at a minimum climbing speed of 1. Creatures that are skilled in climbing can still climb this surface with their normal climbing speed.
Challenging
Challenging surfaces can only be climbed by creatures skilled in climbing. They can only be climbed at a minimum climbing speed of 1.
Swimming
Any creature with at least two hands (or hand-like limbs, like tentacles) can swim at half of its movement speed rounded up. Creatures of aquatic nature, like fish, can swim at their full movement speed.
Currents
Sometimes, the waters you are trying to traverse have a current. In this case, your swimming speed will either be halved or doubled, depending on whether you are swimming with or against the current.
Flying
Winged creatures can fly at the same speed as their walking speed by default. Unless specifically mentioned otherwise, a creature can end its turn mid-air. Wings are not necessary to take flight; however, creatures that are capable of flying without wings will have that ability mentioned in their description.