Inversion of control is a broad term but for a software developer it's most commonly described as a pattern used for decoupling components and layers in the system.
For example, say your application has a text editor component and you want to provide spell checking. Your standard code would look something like this:
public class TextEditor {
private SpellChecker checker;
public TextEditor() {
this.checker = new SpellChecker();
}
}What we've done here creates a dependency between the TextEditor and the SpellChecker. In an IoC scenario we would instead do something like this:
public class TextEditor {
private IocSpellChecker checker;
public TextEditor(IocSpellChecker checker) {
this.checker = checker;
}
}You have inverted control by handing the responsibility of instantiating the spell checker from the TextEditor class to the caller.
SpellChecker sc = new SpellChecker; // dependency
TextEditor textEditor = new TextEditor(sc);
