Short answer
Your first period means you have reached puberty (bulugh). From now on the five prayers, the Ramadan fast and hijab are fard on you, and you are now accountable for what you do. In the Hanafi school bleeding counts as a period only from the age of 9 and for at least 3 days. Early periods are often irregular, so keep a record.
Bulugh for a girl is established by menstruation, by a wet dream with fluid, or by pregnancy; with no sign, at 15 lunar years on the fatwa view. The minimum age for haid is 9 lunar years; blood before then is istihadah. For a first-time bleeder (mubtada'ah), up to 10 days is haid; if it continues beyond 10, the first 10 days are haid and the next 20 days are purity.
The four schools agree on this.
Explanation
This is a normal and blessed step that every woman goes through, including the mothers of the believers. In Islamic law the first period marks bulugh (puberty). The Prophet ﷺ said the pen is lifted from a child until they grow up; from now on you are fully accountable, and your mistakes are written as well as your good deeds.
What becomes fard now:
- The five daily prayers, except during your period, when they are lifted and never made up.
- Fasting in Ramadan, with missed period days made up later.
- Hijab in front of non-mahram men. See is hijab mandatory.
- Ghusl at the end of each period. See when to do ghusl after your period and how to do ghusl.
Counting it. In the Hanafi school a period lasts at least 3 days and at most 10, and the clean gap between two periods is at least 15 days. Bleeding before the age of 9 is not a period. For a first period, with no habit yet, all bleeding up to 10 days is the period. If it goes past 10 days, the first 10 are your period and the rest is istihadah (non-menstrual bleeding), so you do ghusl and pray. If bleeding keeps going for weeks, the Hanafi rule for a beginner is 10 days of period followed by 20 days of purity. See minimum and maximum days of a period.
Start a simple note on your phone with the date and time each period starts and ends. It makes every later question easier. During your period you can still make dua, dhikr and listen to the Quran: see what is not allowed during your period. Parents can read at what age is a child accountable.
The evidence
Quran, Surah An-Noor 24:59
وَإِذَا بَلَغَ ٱلْأَطْفَٰلُ مِنكُمُ ٱلْحُلُمَ فَلْيَسْتَـْٔذِنُوا۟ كَمَا ٱسْتَـْٔذَنَ ٱلَّذِينَ مِن قَبْلِهِمْ ۚ كَذَٰلِكَ يُبَيِّنُ ٱللَّهُ لَكُمْ ءَايَٰتِهِۦ ۗ وَٱللَّهُ عَلِيمٌ حَكِيمٌۭ ﴿٥٩﴾
And when the children among you reach puberty, let them ask permission [at all times] as those before them have done. Thus does Allah make clear to you His verses; and Allah is Knowing and Wise.
Puberty changes a person's duties.
Quran, Surah Al-Baqara 2:222
وَيَسْـَٔلُونَكَ عَنِ ٱلْمَحِيضِ ۖ قُلْ هُوَ أَذًۭى فَٱعْتَزِلُوا۟ ٱلنِّسَآءَ فِى ٱلْمَحِيضِ ۖ وَلَا تَقْرَبُوهُنَّ حَتَّىٰ يَطْهُرْنَ ۖ فَإِذَا تَطَهَّرْنَ فَأْتُوهُنَّ مِنْ حَيْثُ أَمَرَكُمُ ٱللَّهُ ۚ إِنَّ ٱللَّهَ يُحِبُّ ٱلتَّوَّٰبِينَ وَيُحِبُّ ٱلْمُتَطَهِّرِينَ ﴿٢٢٢﴾
And they ask you about menstruation. Say, "It is harm, so keep away from wives during menstruation. And do not approach them until they are pure. And when they have purified themselves, then come to them from where Allah has ordained for you. Indeed, Allah loves those who are constantly repentant and loves those who purify themselves."
Menstruation has its own rulings.
Sunan Abi Dawud 4398
Graded sahih... رفع القلم عن ثلاثة عن النائم حتى يستيقظ ...
"The pen is lifted from three: the sleeper until he wakes, the afflicted until he recovers, and the child until he grows up."
Accountability begins at puberty.
Sunan Abi Dawud 641
Graded sahih... لا يقبل الله صلاة حائض إلا بخمار ...
"Allah does not accept the prayer of a woman who has reached puberty except with a head cover."
A girl who has begun menstruating is under the rulings of an adult woman.
Where the ruling is recorded
- al-Durr al-Mukhtar, Kitab al-Hajr, chapter on puberty. Signs of a girl's puberty, and 15 years as the age when no sign appears, on the fatwa view.
- Radd al-Muhtar (Ibn Abidin), Kitab al-Taharah, chapter on haid. The minimum age of haid is 9; a beginner whose bleeding continues counts 10 days of haid and 20 of purity.
Checked by our team. For a more accurate answer to your own situation, consult a scholar. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.