Wikipedia: Jewish Prayer
Orthodox Judaism regards halakha as requiring Jewish men to pray three times daily... Orthodox Jewish women are required to pray at least daily, with no specific time requirement, but the system of multiple daily prayer services is regarded as optional. (Footnote: This view is based on Maimonides' view.) Conservative Judaism also regards the halakhic system of multiple daily services as mandatory. Since 2002, Conservative Jewish women have been regarded as having undertaken a communal obligation to pray the same prayers at the same times as men, with traditionalist communities and individual women permitted to opt out. Reform and Reconstructionist congregations do not regard halakha as binding and hence regard appropriate prayer times as matters of personal spiritual decision rather than a matter of religious requirement.
According to the Talmud women are generally exempted from obligations that have to be performed at a certain time...
Orthodox authorities have been careful to note that although women have been exempted from praying at specific fixed times, they are not exempted from the obligation of prayer itself... Many Jews rely on the ruling of the (Ashkenazi) Rabbi Avraham Gombiner in his Magen Avraham commentary on the Shulkhan Arukh, ... that women are only required to pray once a day, in any form they choose, so long as the prayer contains praise of (brakhot), requests to (bakashot), and thanks of (hodot) God.
רמב"ם פירוש המשניות קידושין א:ז
ומצות עשה שהזמן גרמה היא שחובת עשייתה בזמן מסויים, ושלא באותו הזמן אין חיובה חל ... וכבר ידעת שכלל הוא אצלינו אין למדים מן הכללות, ואָמְרוֹ "כל", רוצה לומר על הרוב, אבל מצות עשה שהנשים חייבות ומה שאינן חייבות בכל הקפן אין להן כלל אלא נמסרים על פה והם דברים מקובלים, הלא ידעת שאכילת מצה ליל פסח, ושמחה במועדים, והקהל, ותפלה, ומקרא מגילה, ונר חנוכה, ונר שבת, וקדוש היום, כל אלו מצות עשה שהזמן גרמה וכל אחת מהן חיובה לנשים כחיובה לאנשים.
Rambam, Commentary on Mishnah Kiddushin 1:7
And a positive time-bound commandment is obligatory at a set time, and outside of this time, its obligation does not take effect... You already know that we have a principle that one does not learn from (heuristic) rules, and the term “all” (in the statements about women and positive commandments) truly means “most.” The specific details of women’s obligation in positive commandments have no general rule, rather they are passed on by tradition. Is it not the case that eating matzah on the first night of Pesah, joy on the festivals, the public reading of the Torah every seven years, tefillah, reading of the megillah, lighting Hanukkah candles, lighting Shabbat candles, and reciting kiddush are all positive time-bound commandments and for each of them a woman’s obligation is the same as a man’s obligation.
“Who do not make havdalah” – Even though they are obligated in the Amidah, as is written in Siman 106, nonetheless, most do not have the practice of praying at the end of Shabbat. Perhaps this is because the evening prayer is optional, save the fact that Jews accepted it upon themselves as obligatory, and women never obligated themselves to pray at the end of Shabbat.