Data cabling is classified in a number of different categories known as Cat5e, Cat6 etc. The category refers to the performance specification of the cabling system.
A higher category represents a higher performance level. So for example, a compliant Cat6 system is guaranteed to perform to a higher specification than Cat5e.
Apart from performance, the physical formats of the systems are the same. For example, all categories use 4-pair cables and apart from Cat7/7a, the standard connector is the 8-pin RJ45.
Components are also normally backwards compatible, so a Cat5e patch lead may be used with a Cat6a system, but the resulting system will only perform to the lowest performing component, Cat5e in this case.
For more detailed information about each category of data cabling, click on the links on the right of this page. Alternatively download the attached 2-page reference flyer.