Rambam lays out the laws of tzitzit, including when the obligation applies and how it is observed on garments with four corners.
וּמֻתָּר לְהִכָּנֵס בְּצִיצִית לְבֵית הַכִּסֵּא וּלְבֵית הַמֶּרְחָץ. נִפְסְקוּ לוֹ חוּטֵי לָבָן אוֹ תְּכֵלֶת זוֹרְקוֹ בָּאַשְׁפָּה מִפְּנֵי שֶׁהִיא מִצְוָה שֶׁאֵין בְּגוּפָהּ קְדֻשָּׁה. וְאָסוּר לִמְכֹּר טַלִּית מְצֻיֶּצֶת לְגוֹי עַד שֶׁיַּתִּיר צִיצִיּוֹתֶיהָ. לֹא מִפְּנֵי שֶׁיֵּשׁ בְּגוּפָהּ קְדֻשָּׁה אֶלָּא שֶׁמָּא יִתְעַטֵּף בָּהּ וְיִתְלַוֶּה עִמּוֹ יִשְׂרָאֵל וִידַמֶּה שֶׁהוּא יִשְׂרָאֵל וְיַהַרְגֶּנּוּ. נָשִׁים וַעֲבָדִים וּקְטַנִּים פְּטוּרִין מִן הַצִּיצִית מִן הַתּוֹרָה. וּמִדִּבְרֵי סוֹפְרִים שֶׁכָּל קָטָן שֶׁיּוֹדֵעַ לְהִתְעַטֵּף חַיָּב בְּצִיצִית כְּדֵי לְחַנְּכוֹ בְּמִצְוֹת. וְנָשִׁים וַעֲבָדִים שֶׁרָצוּ לְהִתְעַטֵּף בְּצִיצִית מִתְעַטְּפִים בְּלֹא בְּרָכָה. וְכֵן שְׁאָר מִצְוֹת עֲשֵׂה שֶׁהַנָּשִׁים פְּטוּרוֹת מֵהֶן אִם רָצוּ לַעֲשׂוֹת אוֹתָן בְּלֹא בְּרָכָה אֵין מְמַחִין בְּיָדָן. טֻמְטוּם וְאַנְדְּרוֹגִינוּס חַיָּבִין בְּכֻלָּן מִסָּפֵק לְפִיכָךְ אֵין מְבָרְכִין אֶלָּא עוֹשִׂין בְּלֹא בְּרָכָה: הֵיאַךְ חִיּוּב מִצְוַת הַצִּיצִית. כָּל אָדָם שֶׁחַיָּב לַעֲשׂוֹת מִצְוָה זוֹ אִם יִתְכַּסֶּה בִּכְסוּת הָרָאוּי לְצִיצִית יַטִּיל לָהּ צִיצִית וְאַחַר כָּךְ יִתְכַּסֶּה בָּהּ. וְאִם נִתְכַּסָּה בָּהּ בְּלֹא צִיצִית הֲרֵי בִּטֵּל מִצְוַת עֲשֵׂה. אֲבָל בְּגָדִים הָרְאוּיִים לְצִיצִית כָּל זְמַן שֶׁלֹּא יִתְכַּסֶּה בָּהֶן אָדָם אֶלָּא מְקֻפָּלִים וּמֻנָּחִים פְּטוּרִין מִן הַצִּיצִית שֶׁאֵינָהּ חוֹבַת הַטַּלִּית אֶלָּא חוֹבַת הָאִישׁ שֶׁיֵּשׁ לוֹ טַלִּית:
It is permissible to enter a lavatory or a bathhouse [wearing] tzitzit. If one of the strands of white or techelet becomes torn, it may be discarded in a garbage dump, because tzitzit is a mitzvah which does not confer sanctity on the article itself. It is forbidden to sell a garment with tzitzit to a gentile until he removes the tzitzit, not because the garment possesses a measure of holiness, but because we are concerned that he will dress in it, and [unknowingly,] a Jew will accompany him, thinking that he is a fellow Jew, and the gentile may kill him. Women, servants, and minors are not required by the Torah to wear tzitzit. It is, however, a Rabbinical obligation for every child who knows how to dress himself to wear tzitzit in order to educate him to fulfill mitzvot. Women and servants who wish to wrap themselves in tzitzit may do so without reciting a blessing. Similarly, regarding the other positive commandments which women are not required to fulfill, if they desire to fulfill them without reciting a blessing, they should not be prevented from doing so. A tumtum and an androgynous are obligated in all positive commandments because of the doubt [about their status]. Therefore, they fulfill [all these positive commandments] without reciting a blessing. What is the nature of the obligation of the commandment of tzitzit? Every person who is obligated to fulfill this mitzvah, if he wears a garment requiring tzitzit, should attach tzitzit to it and then wear it. If he wears it without attaching tzitzit to it, he has negated [this] positive commandment. There is, however, no obligation to attach tzitzit to a garment which requires tzitzit, as long as it remains folded in its place, without a person wearing it. It is not that a garment requires [tzitzit]. Rather, the requirement is incumbent on the person [wearing] the garment.