I have seen a function named implicitly used in Scala examples. What is it, and how is it used?

Example here:

scala> sealed trait Foo[T] { def apply(list : List[T]) : Unit }; object Foo {
   ...

An implicit question to newcomers to Scala seems to be: where does the compiler look for implicits? I mean implicit because the question never seems to get fully formed, as if there weren't words f...

I have seen a function named implicitly used in Scala examples. What is it, and how is it used?

Example here:

scala> sealed trait Foo[T] { def apply(list : List[T]) : Unit }; object Foo {
   ...

import scala.collection.mutable

case class Node(id: String, children: Seq[Node])

val tree = Node("foo", Seq(Node("bar", Seq()), Node("baz", Seq(Node("qux", Seq())))))
val treeSer = NodeSerializer
val treeStr = treeSer.serialize(tree)
println(treeStr)
val treeData = treeSer.deserialize(treeStr)
println(treeData)
assert(treeData == Some(tree))

trait Serializer[A] {
 def serialize(data: A): String
 def deserialize(str: String): Option[A]
}

object IdSerializer extends Serializer[String] {
 def serialize(data: String): String = {
   s"$data"
 }
 def deserialize(str: String): Option[String] = {
   val pattern = "(.*)".r
   str match {
     case pattern(data) => Some(data)
     case _ => None
   }
 }
}

case class SeqSerializer[A](S: Serializer[A]) extends Serializer[Seq[A]] {
 def serialize(data: Seq[A]): String = {
   data.map(S.serialize).mkString("[", ",", "]")
 }
 def deserialize(str: String): Option[Seq[A]] = {
   val pattern = "^\\[(.*)\\]$".r
   str match {
     case pattern(data) =>
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