This has seen a drive to add personalization features to automated marketing campaigns as well as in the content management system (CMS). CMSs have therefore evolved to accommodate this need, moving from platforms to manage and serve content to also service digital experiences which are personalised. This has seen the emergence of digital experience platforms (DXP) which need to orchestrate the personalization process. Related buzzwords in this space include "Content as a Service" (CaaS) and "headless" or "decoupled".
Personalization trends
A look at Google Trends for "content personalization" emerged from a low base around 2013 to hit a peak around 2020. Interest in the term is still elevated today, however it does seem to have reached its peak. This perhaps represents attention moving to other hotter topics such as DXP and CDP.

This trend has also been seen in the Drupal community. The concept of "Web Experience Management" first appeared in the Drupal community around 2011 and was popularised by Dries in his keynote at DrupalCon Portland in 2013.
This marked the beginnings of the shift in the community. On particularly visionary presentation was given by Dave Ingram, Delivering Hyper Personal Digital Experiences Within Drupal, where he set out a recipe for personalization which covers all of the bases for personalization techniques as well as a sensible approach for iterating and improving over time.
The concepts of segmentation, engagement and personalization were beginning to take hold. However, prior to 2015 there was only the occasional article or presentation on the specific subject of personalization. From 2015 interest certainly picked up, with more Drupal personalization presentations being given at Drupal conferences and camps. In 2020 in was a very hot topic at DrupalCon, with many presentation given from a variety of Drupal agencies.
Early personalization efforts were based around tracking a logged in user and serving a personalized experience to them based on their properties. Users could signal their interests by explicitly selecting them on their user profile or signing up to various groups. CRM systems could also be integrated with Drupal to sync user profiles of known users. In this light personalization is relatively easy as the user is known and already a customer. Recent developments have been around personalizing for anonymous users and this has lead the need for a more decentralised approach to tracking and the delivery of the personalised experience. This need to personalize for unknown users could be considered as the main driver for the activity in the space since 2015.
A lot of this interest has been driven in the emergence of Acquia Lift (now Acquia Personalization). This product saw a lot of promotional activity from Acquia which, whilst being targetted at potential customers, was also helpful in educating the Drupal community around the need for personalization and also some of the approaches that could be taken to achieve that. This lead to the development of modules based around user context and the conditional serving of content.
That is not to say the rest of the community has sat idly by. There are a number of Drupal agencies which have picked the concept up and integrated it into their practices, driving the way they communicate with clients about the needs for personalization and how it can be achieved. In the presentations below there is a fairly even split between strategy and technology. It is refreshing to see that the problem of personalization has been seen as multifaceted with a strong emphasis on research, planning and design, as well as the technology to achieve it.
This has lead to the development of a number of open source projects in the Drupal space which can be used for personalization projects. Some of these are simple client side solutions, sometimes adopting a decoupled approach to serving the personalized experiences. We have also seen increased integrations with CRMs, marketing tools and CDPs to serve the personalized content.
Conclusion
This article is a roundup of most of the events and presentations which have helped shape the way Drupal practitioners approach the conceptual and technical solutions required for Drupal personalization. If you have any items you think I have missed in the roundup below, please add them to the comments and I will look to incorporate them in.
What is next for personalization in Drupal? Time will tell.