Often personas are described as archetypes of your target groups. But what does this mean?

The target group is more or less known. For instance it is college graduates or women between 30-40.
Target groups have their value but fall short by describing the needs, triggers, values, and requirements of potential individual customers. A persona gives the target group a face, history and biography. Personas will indicate whether or not the customer would buy and why.

The difference between target groups and personas

A simple way to understand the differences between target groups and personas is to define a target group and its results. For instance:

British
There are quite some Brits around. 66.47M in 2018. However this does not define an effective target group.
Narrow it down further by targeting British people, male and divorced. No exact statistics could be found, but still no exact target group.
Narrow the targets a bit further: Male Brits divorced one or more times whom live in a castle.

This makes for a finite homogeneous target group, doesn`t it?

Resulting in two prominent members of the target group:
Ozzy Osbourne - Prince of Darkness
and
Prince Charles - Prince of Wales and heir apparent to the British throne.

Would you address both gentlemen in the same manner?

Here is where personas chime in:
Personas put a face to the abstract description provided by the target groups and helps address people behind the numbers in a way that engages them with your content, makes them buy or sign up. This implicit customer centricity shaped the idea of personas.

Kathy


The origin of personas can be traced back to 1983 and Alan Cooper.
In an article of the same title he described, how he grew the idea behind personas. Back then, computers were slow. At least once a day, Cooper working as a software developer needed to compile a large project management tool. Thus during that wait time he would walk and engage in a fictional conversation with a non-fictional user he named Kathy.

He discussed with Kathy problems in usability, she faced while using the project management tool. As a result he used these insights to further develop the software, which became a large success.

Chuck, Cynthia and Rob

After 1995, Cooper then a consultant, challenged with helping one of the first Business Intelligence tool vendors to get a grasp of their customers. He started interviewing potential clients of the BI tool and figured out that most fell into three distinct groups. Goals, tasks and skill level. Hence three personas were created, Chuck, Cynthia and Rob.
Cooper called personas his secret interaction design weapon and started utilizing it in all of his projects. Witnessing developers talk about personas and what they would do or if they would understand a feature. Learnings during this process led Cooper to publish in 1998 "The Inmates Are Running the Asylum", which is now the standard.

Subsequently, personas became a wild success across industries and organization . They are being utilized in everything from marketing to development, whenever a customer focus is needed.