Just as a hammer needs a nail, a user interface is there to help your user carry out an action.

Whether you’re designing a website that summarises the plot of Game of Thrones or an app that turns your phone into a strobe light, you want your users to utilise your design to perform an activity. Whatever it is, you want to persuade your user to use your design to complete that action so that your tool is useful to them and they keep using it.

One thing inexperienced designers commonly forget is actually telling their users to do the thing they want them to do. Whether that’s a whole paragraph of ‘next steps’ instructions or a big, bold button labelled BUY NOW, you’ll invariably find your design is less effective without it.

This was initially discovered by Mad Men-style marketing executives back in the 60s. Their target audience would be flipping through their Sunday newspapers, reading up on the economy and how awful hippies were, when they’d come across a page proselytising about how amazing Coca Cola tastes. Their reaction would be “oh, how interesting” and they would turn the page. On the other hand, when the ad’s writers added a big logo at the bottom of the page saying “drink Coca Cola,” suddenly readers were flocking to the market to try out this delicious drink.

Hence, marketing teams introduced a steadfast rule that you should always end your advert with a ‘call to action’, telling your readers to buy your product. It’s simple human nature that, once a person has finished reading a page, their next two questions will invariably be “what’s your point?” and “what do I do now?”.

The answer to those questions should be your call to action and any attempt to direct a user to a goal is incomplete without it. An advert without a CTA is like a joke without a punchline.

As we entered the digital age, this wisdom was copied by UX designers and now all our pages have that aforementioned big BUY NOW button as a call to action. Unfortunately, that wisdom still puts that button at the bottom of the page in many cases.

You see, I don’t know about you, but I don’t sit down at a computer and read through a whole website like a newspaper. When I find something I want to buy on Amazon, I don’t read every word of the page from top to bottom and then, finally, click the button to buy. I skim the text, flick back to the pictures, go down to check something in the text, back up to the price, down to the technical specifications and then back to the pictures. I might decide to buy while looking at any part of the page and I don’t want to have to scroll down to the bottom looking for that button.

Then again, what if I like that product so much, I want to go back to that page later to buy another one? Do I have to then scroll all the way back to the bottom of the page to find that ‘buy’ button again? Do I have to sit through the sales pitch when I already know I want to buy? Of course not. Amazon, sensibly, put their ‘buy’ button on the right side of the page at the top, where it’s easily accessible from the second you load the page.

Still, Amazon try to keep their important content above the fold, so it can all be seen when the page loads without you having to scroll. If you need to load a page with more text than you can fit above the fold, then where do you put your call-to-action button? Put it at the bottom and the user won’t see it until they scroll and they might not be able to find it; but If you put it at the top of the page, you leave the user stranded without it in sight once they’ve scrolled down.

Well, if you had to choose, I’d still say you’re better off with the button at the top. Not only does this cater to repeat visitors, but it also means that users see where the button is before they lose sight of it, meaning they know where to go back to it. However, who said you had to choose?

You could easily put a button at the top of the page and at the bottom of the page, meaning there’s always a button in sight, no matter where you are in the text. This solves your issue, but it could also leave the user confused. How does the user know both buttons do the same thing? They might end up clicking both to test them out and wasting their time.

Far better would be to add a single, dynamic button that followed the user up and down the page as they scroll, ensuring that the call to action is ever-present, always directing the user to the goal and always ready to accept that all-important click. The same applies to phone numbers to call, places to visit, times to tune in or just instructions to follow – keep the actions you want the user to take in their view at all times.

Just take a look at Twitter to see how their ‘compose tweet’ button remains on the screen wherever you go in the app.

There’s still room for flexibility in your design. Whether you have a static column with your CTA in constant view while your text moves in a scrolling column next to it, or add a link that returns to the top of the page where the button is in view from anywhere you can scroll to. However you keep the CTA in your customers’ view, it will increase user engagement and improve the experience.

The most important part of any user journey is the goal at the end and keeping that as the centre of your design will keep your users on track. So the call to action for this article is to look at your site and check your CTA is clear and in full view at all times.