Random Encounters, enemy encounters that occur suddenly when traveling on foot and in some vehicles, are a recurring element of the Dragon Quest game series series. As indicated, random encounters can occur at any time when walking on the overworld or in a dungeon.
The enemies a player can meet varies both on where they are in the game and the terrain they are on. For example, the forest may contain enemies not found in the plains. For games that include travel by ship, enemies encountered while at sea are from an entirely separate set. Some enemies have a very low encounter rate and thus are almost impossible to find; these usually give out large amounts of Experience Points or some other significant reward, the most obvious example being the Metal Slime.
Abilities such as Taloon's Padfoot enable players to avoid or reduce the probability of Random Encounters if the player does not wish to fight in order to save time or HP. Random encounters can be prevented all together for a short time through use of the Holy water item or the spell Holy Protection. In the games that it's available in, the Gospel ring when equipped by a currently active character will remove random encounters altogether.
Similarly, if he wishes to battle more (perhaps for EXP), he might use other abilities increase the probability of having a Random Encounter, or, such as in the case of Whistle, or the Silver Harp, cause one immediately. As an opposite of Holy water, use of Musk or Monster munchies will increase the random encounter rate.