The mishna teaches that we read four special Torah portions, arba parashiyot, in the weeks leading up to Purim and Pesach: Shekalim, Zachor, Para, and Ha-chodesh.

…Since in Nissan they need to bring sacrifices from the new donations, we read earlier, on the first of Adar…

...On the first of Adar we are reminded that our connection with the Jewish people could come across through our common goals – through the mahatzit hashekel….It is up to us to acknowledge the role we seek as part of the Jewish nation, and ensure that the goals which unite us are the correct ones...

…Parashat Zachor should be read on the Shabbat adjacent to Purim, to juxtapose the blotting out of Amalek with the blotting out of Haman. "Para aduma" - to alert Israel to purify themselves, so as to make their Pesach offerings in purity. "On the fourth, Ha-chodesh ha-zeh lachem" - for the portion of the Pesach offering is there.

…Parashat Shekalim and Ha-chodesh are not on a Torah level.

The portions of Shekalim and Ha-chodesh are only a rabbinic obligation, and women are exempt. Note: Because they are a time-bound commandment, to read them in the month of Adar.

For there is a reading that is on a Torah level, such as Parashat Zachor and Parashat Para Aduma and the like.

In the portions that we are obligated to read on a Torah level, such as Zachor.

There are those who say that we are obligated to read Parashat Zachor and Parashat Para Aduma on a Torah level …

Magen Avraham 685

For it [Para] is not on a Torah level, for there is really no reason from the Torah for its reading, and I also do not know where there is any hint [to it].

Parshat Para. There are those who say it is on a Torah level, and according to this one can say that women are also obligated to hear this portion. And there are those who say that this mitzva is only rabbinic, and according to this, women are exempt.

Remember that which Amalek did to you on the way as you went out of Egypt. That he happened upon you on the way, and cut off the stragglers behind you when you were faint and tired, and he did not fear God. And it will be when the Lord your God gives you rest from all of your enemies around, in the land that the Lord your God gives to you as an inheritance to take possession of, you shall blot out the memory of Amalek from beneath the heavens. Do not forget.

"Remember"- with the mouth. "Do not forget"- with the heart

It is a positive commandment to destroy the memory of Amalek, as it is said "blot out the memory of Amalek" and it is a positive commandment always to remember his bad deeds and his lying in ambush, in order to arouse loathing towards him, as it is said "remember that which Amalek did to you". From Oral Tradition we learn "Remember"- with the mouth. "Do not forget"- with the heart, for it is prohibited to forget to have loathing and hatred of him.

While Mordechai and Esther demonstrate the characteristics that create Jewish leadership, Amalek, represented here by Haman, demonstrates the antithesis of those values....They believed events are circumstantial, with no Divine providence, thereby allowing them to attack the Jews and, unlike the other nations, disregard the Divine events that transpired in Egypt....They did not fear G-d... [Amalek] is also the antithesis of righteousness and concern for others.... The nation attacked the Jews when they were most vulnerable.......Finally...[w]hile Jewish tradition and Torah are passed down from generation to generation, Amalek must be forgotten.

That we are commanded to remember what Amalek did to Israel…Among the roots of the mitzva: To place in our hearts that anyone who afflicts Israel is hated before God, and his fall and the evil that will befall him will be in accordance with his evil and the accumulated harm he does, as you find with Amalek…Among the laws of the mitzva: That which our sages said, that the obligation of remembering is with the heart and the mouth… We do not know of a set time in the year or in the day for this remembrance with heart and mouth …For this, it is enough for us to remember the matter once a year or every two or three years. For in all the places of Israel they read the sefer Torah over the course of one or two or three years at the least, and thus they discharge this mitzva. Perhaps we can say that the custom of Israel of Parashat Zachor, to read it on a special Shabbat every year, is authoritative and it is because of this mitzva that they established it thus…

…that this applies to a case where ten [are required] on a Torah level, like reading Parashat Zachor, which is on a Torah level…

There are those who say that the fundamental mitzva is to read it publicly. According to this view, one must understand how this remembrance, whose mitzva is communal, differs from other remembrances. One must say that since the intention of the remembrance is to avenge God's vengeance upon these sinners, this is a matter incumbent upon the community.

There are those who say that there is a Torah-level obligation to read Parashat Zachor and Parashat Para Aduma. Therefore, members of small communities that do not have a minyan must come to a place that has a minyan on these Shabbatot in order to hear these parashiyot, which are on a Torah level. Rema: And if it is impossible for them to come, they should still take care to read them with their [proper] tunes and accents…

He [Rema] means that, if they have [a sefer Torah], they should read them from a sefer Torah but without a beracha since there is no minyan, and if they don't have a sefer Torah, they should read them from a printed chumash.

This mitzva is practiced in every place and in every time, among men, because it is for them to make war and take revenge on the enemy, and not for women.

…Parashat Zachor with ten [men] and with a sefer Torah is rabbinic, but from the Torah it is enough that each individual mention verbally, and this is clear. Sefer Ha-chinuch exempts women from this mitzva and it seems a bit as if he exempts them from the prohibition [not to forget] as well. This is not clear in Rambam, and one needs a proof to exempt women from a positive commandment that is not time bound, especially when there is also an accompanying prohibition. That which he wrote – that "it is upon them [men] to make war and not upon women" – actually, for an obligatory war everyone goes out, even a bride from her wedding canopy as is explained in the mishna. Also, who has access to the secrets of God [to know with certainty] if the rationale is to promote the vengeance? For it is possible that it is a decree of the Torah for whatever reason that we remember hating him for some reason that we don’t know, and it is possible even when our Moshi'ach comes, who will cut off Amalek entirely such that there will be nothing left of them, that in any case the remembering will always be a positive commandment as well as not to forget. Therefore, it requires further investigation that he exempts women from this positive commandment…

Women are not obligated to hear Parashat Zachor…But they [women] are obligated in the fundamental mitzva to remember the act of Amalek, for it is not a time-bound mitzva and women are obligated. That which we read it before Purim is only a rabbinic enactment as mentioned previously, and also if they [women] come to hear it [Parashat Zachor] they receive a reward…

I received a tradition from Admor Rav Avraham Bing z"l, head of the Beit Din of Wurtzberg, in the name of his pious rabbi, Rav Natan Adler, that women are obligated, and that he was particular that even his housemaid needed to hear Parashat Zachor and so I practiced according to him. His reason, in my humble opinion, is because it is not a positive time-bound commandment for there is no specific requirement regarding what time it is read…Just that one read it once a year, and therefore it is like other positive commandments that are not time-bound in which women are obligated….Why shouldn't the mitzva of remembering Amalek apply to women? Even though they are not active participants in war, it is possible that remembering the hatred [among women] will prove useful for blotting out [Amalek], as the acts of Esther prove…

There are those who wrote that… she [a woman] can read for herself from a Sefer Torah without a congregation, but in practice, one should be stringent not to read from a sefer Torah for a woman or even for ten women…

It is permissible to take out a sefer Torah especially for the women (at a time afterward [after the reading during prayer]) to read Parashat Zachor for them without a beracha.

In practice they follow the opinion of the majority of halachic authorities that women are obligated to hear this parasha through a Torah reading, and the custom has spread thus in most congregations, that women come to synagogue to hear the reading of Parashat Zachor. And in any case to read only for women, a number of great later authorities think one should be stringent not to read only for women, even for ten women, as is written in Mikra'ei Kodesh. Indeed, just as his honor wrote, in Ashkenaz the custom is to read only for women, but certainly one should not recite a beracha since some authorities think they are exempt…