Web 2.0 describes the second evolutionary stage of the World Wide Web. While the beginning of the commercial Internet age was characterized by one- and two-dimensional communication, Web 2.0 is characterized by user interaction with the website and communication with one another via web services. Social networks are among the greatest innovations of Web 2.0.

Background and Development
The origins of the commercial Internet as we use it today date back to the late 1980s and early 1990s. This time was mainly characterized by the fact that users could retrieve content from static websites or use the World Wide Web to send e-mails. Communication was mainly monodirectional. With the advent of e-commerce, chat systems or Internet forums, mutual communication between providers and users could take place. Users themselves could also communicate with each other via the web. To date, we are talking about the late 1990s, when web content was mainly designed by experts. At that time it was still too complicated for private users to set up their own website or run forums. What is eventually referred to as Web 2.0 was an important evolutionary step. Because in the early 2000s, users could suddenly produce their own content via blogs and social media platforms without having to have in-depth knowledge of HTML or special programming languages. This is also referred to as “Customer Created Content”. Services like WordPress established itself at this time. In addition, new technologies such as RSS offered the possibility of content syndication, i.e. the distribution of content on the web. Web 2.0 is closely associated with the term “Social Web”. This is due to the fact that social media, a very separate area of the World Wide Web, has developed at least since the founding of Facebook. Via these platforms, it was now possible for users to exchange information directly and thus find online communities.
The term Web 2.0 was coined by Tim O’Reilly, who developed it during brainstorming prior to a conference. Against the background of the bursting of the dot-com bubble in 2001, he wanted to use Web 2.0 to set an optimistic sign for a new beginning of the WWW.
Characteristics
Web 2.0 is characterized above all by the fact that the user no longer only passively consumes content, but also creates it himself and actively exchanges information with other users. The characteristics of Web 2.0 include:
- the development of the blogosphere with a variety of different blogs, free blog systems such as Blogger or WordPress
- the establishment of techniques for distributing content such as RSS feeds
- the development of a vlogosphere with portals such as YouTube, in which, analogous to the blogosphere, video content is used instead of text
- the development of social networks, above all Facebook, which enable users to create their own content, create their own communities and exchange information with the help of photos, films or audio files
- the distribution of podcasts
- the mass use of file sharing networks and P2P networks
- the start and the enormous further development of Wikipedia as the first online encyclopedia, in which not only scientists, but in principle everyone can write
- the development of chat rooms in which users can communicate with each other on the web
- the launch of social bookmarking , which allows users to save their favorite URLs online and share them with others
With regard to the technical aspect, Web 2.0 is also characterized by the fact that most applications are now browser-based. This means that the user no longer has to download special software in order to use web services, but can start or change it via his web browser. One of the negatively connoted characteristics of Web 2.0 is that the internet user has more opportunities to actively participate in the design, but on the other hand, more and more data about him can be found on the internet. Any person can thus become a “public” person if he moves on the Internet.
Consequences for SEO and online marketing
Due to the consistent further development of the World Wide Web, many marketing branches such as social media marketing or online recommendation marketing have only just developed. At the same time, the search engine optimization more and more complex and diverse due to the new diverse possibilities. So-called “social signals” were now theoretically included in the calculation of the popularity or relevance of a page, i.e. user signals that shared or recommended a website via social media. Blogs or social bookmarks offer excellent opportunities for SEOs to generate backlinks. At the same time, companies have now been able to increase their reach enormously via social media. The establishment of the social web has also brought far-reaching changes to CRM. Since then, users have been able to publicly express their opinions on products or services. Consequently, since the introduction of Web 2.0, it has become all the more important for many companies to pay attention to the development of their reputation in order to avoid modern phenomena such as the shitstorm.