When I run `w` - to see who is logged on and what they are doing, i see this: 

```
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU WHAT
 user  tty7     :0               08:14   10:32m 44:10   0.50s gnome-session
 user  pts/0    :0.0             09:15    9:30m  0.24s  0.24s /bin/bash
 user  pts/1    :0.0             14:14    4:32m  0.20s  0.20s bash
 user  pts/5    :0.0             18:27    9:24   0.28s  0.28s bash
 user  pts/7    :0.0             18:35    9:57   0.40s  0.40s bash
 user  pts/8    :0.0             18:37    0.00s  0.22s  0.00s w

```

What are the `pts/` ?