If you are familiar with our blog, or our approach to online marketing, then you already know why we attach so much importance to marketing personas.

They help us to know our clients as individuals, and real people with concrete buying motivations, rather than a faceless virtual crowd that chooses randomly to either do business with us or not. In other words, they hold the key to personalized marketing and make it possible to craft offers that buyers respond to.

For that reason, focused thought and research need to go into creating each persona. Further, it isn't unusual for a company to have multiple personas to work with. Persona information isn't just details, it's a proprietary edge that a business can hold on to and use time and time again to grow their online marketing plans.

That doesn't mean that personas should never change, however. In fact, for your marketing to stay relevant and insightful, your personas must shift and adjust on a regular basis. That's because they are like maps that, slowly but surely, will go out of date over time if they aren't revisited.

To give you a sense of why and how marketing personas have to change and evolve over time, here are a few of the most important reasons:

You gain a better understanding of your customer base.

The longer you are in business, the easier it will be for you to really know your customers and their needs. As your understanding of your different buyer groups changes over time, so should your personas.

Your customers themselves are changing.

In some markets, the key buyers and decision-makers can change from one time period to the next. As an example, think of real estate and sticking to one neighbourhood, where younger couples might arrive with new needs and expectations of a first home. The same can be true of virtually any other industry, and it's important that your marketing personas reflect these types of demographic shifts.

You are trying to aim at a different segment of the market.

Sometimes, your marketing personas have to change simply because you're trying to reach different people than you were in the past. Every time you open up to a new group of buyers, or launch a new campaign aimed at a different product or service, you should update your marketing personas at the same time.

You are looking for bigger sales opportunities.

Similarly, businesses sometimes grow and start looking for bigger sales opportunities (from selling to locations or departments to entire businesses, for example). That means a new set of contacts and decision-makers, with new marketing personas to match.

Your company is trying to attract fewer customers than before.

On the other end of the spectrum, businesses sometimes downscale their marketing, or prefer to concentrate their efforts on a specific segment of the market. That could call for increased segmentation within a specific group of buyers, or more detailed interest in a certain type of customer.

The point, with each of these situations, is that the people you are trying to market to don't exist in a vacuum – they are changing and evolving all the time, and so are their needs and priorities. With that in mind, you have to adjust your marketing personas as well, or risk having your plans and tactics become less and less relevant from one month to the next.

Want to find out how we use marketing personas and creative techniques to produce extraordinary results for our clients? Get in touch with Kayak today and ask for a no-obligation consultation.

Randy is the author of "Findability: Why Search Engine Optimization is Dying + 21 New Rules of Content Marketing for 2013 and Beyond" available on Kindle Reader now.