[Tags] are used to indicate the content of a story. Most are quite obvious:

• [mf] male/female activity
• [mm] male/male (gay) activity
• [ff] female/female (lesbian) activity

If there's more than two individuals involved at once, simply add more 'm' and 'f' characters as necessary: [mmf] [mfff] [mmmmffff]

There are many other tags to indicate content:

• [nc] Non-consensual. Rape or other non-consensual sexual scenes
• [yaoi] Homosexual male subject
• [mast] scene involving masturbation
• [fant] scene involving fantasizing or dreaming
• [toys] scene involving sexual toys
• [bond] scene involving bondage
• [oral] scene involving oral sex
• [anal] scene involving anal sex
• [drug] scene involving drug use (for sexual purposes), most probably for mind control or other behavioral changes
• [mc] mind-control
• [tentacles] scene involving those ever popular naughty tentacles
• [spank] scene involving spanking
• [fd] FemDom. Scene involving female domination
• [md] MaleDom. Scene involving male domination
• [bdsm] [bd] [sm] scene involving bondage/domination/sado-masochism
• [insect] yes... involves sex scene with insect(s)
• [best] scene involving sex with animal(s)
• [cross] scene involving cross-dressing
• [viol] violence (not necessarily non-consensual)
• [fur] furry (human/anthropomorphic)
• [rom] romance!

You can use as many as you like in any combination to indicate what's in your story.