A corporate design (CD) is the red thread of your design. It is the superior guideline for all following advertising and marketing measures. The big master plan so to speak!
Having a master plan is of course never wrong. The advantage: You don't have to reinvent the wheel with every new advertising medium, which saves time and money in the long run!
Plus, you are more effective in your public image, since the recognition effect of your brand works across all media and thus synergy effects can be created. Strong brands are recognisable: What colour is Milka? What does the Apple logo look like? Most people could answer these questions in their sleep.
The CD is thus a conceptual elaboration that gives your brand a central meaning and a creative direction. The result is then a consistent branding.
A good corporate design is flexible and can later be transferred to a wide variety of media - even to those that may not even exist today because they are only invented tomorrow.
Especially in the digital age, requirements can change and the design must be applicable to these new situations as if it had been created for them. Of course, this applies not only to digital, but also to print.
In addition, a good CD is conceptually well thought out and takes the target group into account. It is not arbitrary and does not orient itself to short-lived trends. Therefore it works timelessly or at least has a rather long life span. A famous example is the Nivea brand, which has remained true to its branding since 1925 with only marginal changes.