Salaam people!
Itikaaf is commonly practiced by Muslims in particular during the last 10 days of Ramadan. I'm not sure how this specific act is detailed within the Quran (it appears to be detailed within hadith narrations), but from what i am aware of this is not a conceptual practice. I understand that it is in the Quran that the Prophet would meditate (possibly in a cave).
Now I don't feel there is nothing implicitly wrong in spending 10 days in Ramadan in seclusion meditating and engaging in worship, but it appears that it has been reduced to just that. I have spent 10 days in Ramadan in itikaaf and found it to be very rewarding personally, but I expect that this can be done at any time. In addition, all these rules and regulations appear pertaining to the ritual of itikaaf such as it not being permissible to shower, brush your teeth, go outside the Masjid etc. I find these to be very pedantic and unnecessarily rigid, whereby if you go outside the masjid your itikaaf is void... You find that there is also 'sunnah' itikaaf and 'nafil' itikaaf...
Views please!
Regards,