understanding the usage of e inside carasoul.js

hey guys i was just going through the code of carousel.js and i am a little bit confused , now we it comes to attaching events i ofte see code as follows ::

$('a').click(fuction(e){
    if(e.target.targetNode == $(this)[0])
   //do something
});

I am still a bit confused , who is passing the e ? WHO really is passing that e inside the function ?

also in the plugin code i see things like the below :

Carousel.prototype.keydown = function (e) {
  if (/input|textarea/i.test(e.target.tagName)) return
  switch (e.which) {
    case 37: this.prev(); break
    case 39: this.next(); break
    default: return
  }

an event handler is attached like so :

  this.options.keyboard && this.$element.on('keydown.bs.carousel', $.proxy(this.keydown, this))

another example is here :

  Carousel.prototype.pause = function (e) {
    e || (this.paused = true)

    if (this.$element.find('.next, .prev').length && $.support.transition) {
      this.$element.trigger($.support.transition.end)
    }
    this.interval = clearInterval(this.interval)
    return this
  }

Who is passing e inside these functions , from where is it coming from ? i have absolutly no clue , i have been using JS for a while now , but this still baffles me . can somebody really clear this doubt for me once and for all ?

P.S. I have seen this answer on SO , but it does't answer the questions i have asked . I understand that e is in a way a object with differentv properties that we can access.