Either way, they're well worth using and are a great way to unstick writer's block.
Who? Traditionally, this is taken to mean who is the content about.
But you could equally twist it round to who is the content aimed at.
Keep in mind who your are writing for as you progress through your content creation - this will help stop you getting side-tracked and will help you to focus on meeting the needs of your site visitors.
What? What do you want the content you're creating to do? It needs a purpose - whether that's to inform people or to help move them towards buying something from you or any other purpose that is ethical and makes sense.
A soft drink would likely aim to quench your thirst.
An advert for an alcoholic drink is often more subversive - it has to meet the demands of regulators whilst achieving the purpose of selling you the drink.
Content on your website needs to answer the "what's in it for me" question that will be running through your visitor's mind.
Where? If you're telling a narrative, this can be where the event took place.
If you're creating other content then it can be as simple as where the product or information you're sharing can be used.
So a set of plans for a chicken coop would likely be used at your home or small holding.
A mobile phone could be used anywhere that had a signal.
An all terrain bike could be used in territory that was out of bounds to regular bikes.
And so on.
You should be able to work out the "where" quite easily.
For instance, the information I'm giving here could be used on your website, on a phone app, in a print or radio or television advert or in a direct mail piece.
Or probably quite a few other places.
And if I was short of inspiration this whole piece could be recreated to suit each of those eventualities, with examples to help you to translate things to your needs.
When? In a narrative, this would be like the series 24 perpetually showing you the time to remind you that it's real-time.
If it is a sales letter that you are creating then the "when" could be whilst stocks last, whilst the promotion is on or any other excuse to nudge people into making the purchase decision sooner rather than later.
If you run a service industry or a website that has seasonal variations then you could use the seasons and events like Christmas as an excuse for incorporating the when side of things.
Why? This is maybe the most important of the five questions and can often lead to a complete piece of content on its own.
Why is an incredibly powerful question and one neat way to use it is to question your first - and maybe even second, third and subsequent - answer.
So often we do things because we always have done them.
Asking "why" forces us to re-examine our answers.
As you'll know if you've ever had to explain something that you thought was obvious to a child and find yourself getting more confused than you were prior to being quizzed.
Challenging the status quo by asking "why" can also lead to extra traffic to your newly created content - even if you don't rock the boat deliberately, the chances are that you'll stir up a few questions in people's minds that have been dormant for longer than they'd care to admit.