Sissy dress dates back to Victorian times, when strict matriarchs punished their naughty male children by making them become a forced sissy for a few minutes - forcing them to wear women's clothes in front of the other children. Thankfully this practise has stopped nowadays, and it's just adult males who become sissys consensually! Dressing like a sissy or even a sissy baby can involve just wearing women's underwear or even full outfits. Unlike regular cross-dressing, the point of this is for total abject humiliation of you, the sissy.
Sissy training can be strict. You will be told what to wear and what to do while you wear it. Submission is key, and your mistress will expect you to obey her commands. She may order you to bring her lunch on a tray whilst in your uniform, and you'd better just do it with no attitude. Sissy training takes weeks or even months and you must remember that every dominatrix is different and will expect something different from you.
Ever watched a married couple where the wife lives in the shadow of her husband? What you don't know is that behind closed doors, he may be her sissy. Sissy husbands can appear to be dominant in public to 'save face', but when they are back home, the outfit comes back on and they become subservient. For many men, it's such a relief to be ordered around and not to have to make decisions for themselves. It can also be a massive turn-on for even a seemingly dominant male to be stripped of his power now and then. This role reversal can be massively erotic for the open-minded.