The Use of def, val, and var in Scala Programming

def is used to create a method.
Example:

def adjustedCosineSimilarity(dotProduct: Double, ratingNorm: Double, rating2Norm: Double) = {
  dotProduct / (ratingNorm * rating2Norm)
}

val is used to create a fixed value or constant (a value that cannot be changed).
Example:

val threshold = 0.5

Meanwhile, var is used to create a variable (a value that can be changed).
Example:

var n = 0