A logo is one component of a visual identity. It is an important identifier, but it cannot carry the full responsibility of making a brand distinctive, coherent and useful.
The logo is the signature
A strong logo should be recognisable, appropriate and practical. It needs to work at different sizes, across different media and in different production conditions.
But a brand is rarely experienced as a logo in isolation. It is experienced through layouts, messages, documents, websites, spaces, presentations and repeated interactions.
The system creates the experience
An identity system includes the visual and verbal elements that work together to create a consistent impression. These may include typography, colour, image direction, graphic devices, layout principles, iconography, motion and templates.
The logo helps people identify the brand. The system helps them recognise it before they even see the logo.
Systems need rules and range
Consistency does not mean making every item look identical. A useful system provides enough structure to protect recognition and enough flexibility to respond to different communication needs.
The best identity systems define what stays fixed, what may change and how the elements should combine.
Design for real applications
An identity should be tested against the work the business actually produces. A consultancy may need reports, proposals and presentations. A product brand may need packaging, e-commerce and retail communication. A complex group may need a system that distinguishes divisions while maintaining a shared parent identity.
The quality of an identity is revealed in use, not only in a logo presentation.