switch port types (access, trunk, hybrid ..)

[Mark]

Hello,

usually ports on the L2 switches (I don't know agbout L3) can be configured
in the following modes: access, hybrid or trunk (I think, terminology may
vary among the different vendors). The IEEE 802.1q standard actually
mentiones about these three modes somewhere in appendix, so I think this is
not really a mandatory part so that every switch must follow?

Furthemore, are these modes purely software concepts or they can, and
usually are, implemented on a real hardware?

Thanks !

Mark