The High Bit Rate (HBR) specification is used in various technologies and is to be interpreted as referring to a mode of operation or a special technology with a high bit rate. You can find the specification in DisplayPort, in the various DSL techniques, in the OTH hierarchy, and in All Optical Networks, to name a few.
In the case of DisplayPort and Embedded DisplayPort, the term High Bit Rate (HBR) is understood to be a bandwidth specification. It was already introduced with DisplayPort 1.0 and 1.1 and implemented in the video cards. In the following versions, High Bit Rate (HBR) was replaced by HBR2 and HBR3. Since 2014, HBR2 has been implemented in most video cards, whereas HBR3 was introduced in 2016.
Bandwidth represents the data rate at the output of the DisplayPort. It is a shared bandwidth that can be shared by multiple monitors. The resolution and refresh rate of the individual monitors can be different. The data throughput of HBR2 is 5.4 Gbit/s per lane, and that of HBR3 is 8.1 Gbit/s. The total throughput for four channels is thus 21.6 Gbit/s gross for HBR2 and 32.4 Gbit/s gross for HBR3. Net of overhead, it is 25.9 Gbit/s.