The Book of Ruth is the shortest book of the OT, just four chapters. But it requires an extensive introduction.
In the Tanakh, it is placed in the Ketuvim, the "writings," and comes near the end. However, in the Christian Bible, it is placed between Judges and 1 Samuel, in the midst of what in the Tanakh is called the Nevi'im, or Prophets. This is because it mentions the birth of a grandfather of King David, enabling the monks who compiled the Old Testament to place it chronologically, so that's what they chose to do. For us, it will be the first book we encounter that does not include any violence, although that would not be the case if we were following the order of the Tanakh.
Ruth is particularly noteworthy for featuring female protagonists. There have been a few women before now who have exercised some agency, within the patriarchal structure: Sarah (though Hagar has little agency, she is succored by God); Rachel and Leah; Zipporah; Miriam; the daughters of Zelopehad; Rahab; and of course Deborah, the only woman who exercises the agency and status that normally pertains to a man. (Delilah I would classify more as a tool than an agent.) From a feminist perspective, there is dispute about how to evaluate the story of Ruth. Naomi and her daughter-in-law Ruth make and execute a plan, and get what they want; but they do so fully within the strictures of patriarchal society. In fact, it is only because of patriarchy that their plan is even needed.
The story is structured by levirite marriage. Many people mistakenly believe that Onan's sin was masturbation, but in fact God killed him because he refused to impregnate his brother's widow. The law is that when a man dies, his brother has to marry his widow(s). This both provides for support of the women, and for the maintenance of the late brother's line since any male offspring are considered to be his. As we have seen, this is held to be very important in the culture. Naomi and Ruth may or may not care about that, but as they are both widows they do clearly care that an unmarried woman has no economic prospects (except perhaps to follow the profession of Rahab and Samson's unnamed companion) and is dependent on charity. Neither of their late husbands had a brother, but the levirite system does allow more distant relatives to marry the widow, although it evidently is not an obligation. So they scheme to get Ruth a husband.
Note that romantic love has nothing to do with it. They choose Boaz because he is wealthy and has a kindly character. It turns out he is not Ruth's late husband's closest relative; another man has a superseding claim if he chooses to exercise it, so that has to be worked out.
Finally, and this is definitely a problem for the Biblical literalists, Ruth is a Moabite who has converted to the cult of Yahweh and been accepted into the Israelite community. However, Deuteronomy 23 says clearly that "An Ammonite or a Moabite shall not enter into the congregation of the Lord, even unto their tenth generation shall they not enter into the congregation of the Lord forever." The Midrash gets around this by concluding that the prohibition refers only to men, but that's quite a stretch when you consider that in the Book of Numbers God gets extremely pissed off when Israelite men start having sex with Moabite women. However, that is not the rationale for the prohibition given in Deuteronomy, so it's not completely ridiculous.
In fact, scholars believe that Ruth was written during the Babylonian period, prior to Deuteronomy. So the writer didn't have that problem. One intent of the writer may be to advocate for conversion, perhaps because the population at the time was depleted. Anyway, here's chapter one.
1 In the days when the judges ruled, there was a famine in the land. So a man from Bethlehem in Judah, together with his wife and two sons, went to live for a while in the country of Moab. 2 The man’s name was Elimelek, his wife’s name was Naomi, and the names of his two sons were Mahlon and Kilion. They were Ephrathites from Bethlehem, Judah. And they went to Moab and lived there.
3 Now Elimelek, Naomi’s husband, died, and she was left with her two sons. 4 They married Moabite women, one named Orpah and the other Ruth. After they had lived there about ten years, 5 both Mahlon and Kilion also died, and Naomi was left without her two sons and her husband.
Naomi and Ruth Return to Bethlehem
6 When Naomi heard in Moab that the Lord had come to the aid of his people by providing food for them, she and her daughters-in-law prepared to return home from there. 7 With
her two daughters-in-law she left the place where she had been living
and set out on the road that would take them back to the land of Judah.
8 Then Naomi said to her two daughters-in-law, “Go back, each of you, to your mother’s home. May the Lord show you kindness, as you have shown kindness to your dead husbands and to me. 9 May the Lord grant that each of you will find rest in the home of another husband.”
Then she kissed them goodbye and they wept aloud 10 and said to her, “We will go back with you to your people.”
11 But
Naomi said, “Return home, my daughters. Why would you come with me? Am I
going to have any more sons, who could become your husbands? 12 Return
home, my daughters; I am too old to have another husband. Even if I
thought there was still hope for me—even if I had a husband tonight and
then gave birth to sons— 13 would you wait until they grew up? Would you remain unmarried for them? No, my daughters. It is more bitter for me than for you, because the Lord’s hand has turned against me!”
14 At this they wept aloud again. Then Orpah kissed her mother-in-law goodbye, but Ruth clung to her.
15 “Look,” said Naomi, “your sister-in-law is going back to her people and her gods. Go back with her.”
16 But Ruth replied, “Don’t urge me to leave you or to turn back from you. Where you go I will go, and where you stay I will stay. Your people will be my people and your God my God. 17 Where you die I will die, and there I will be buried. May the Lord deal with me, be it ever so severely, if even death separates you and me.” 18 When Naomi realized that Ruth was determined to go with her, she stopped urging her.
Note that there is no conversion ceremony. Ruth merely declares her allegiance to Yahweh, and she's good to go. All the folderol evidently came later.
19 So the two women went on until they came to Bethlehem. When they arrived in Bethlehem, the whole town was stirred because of them, and the women exclaimed, “Can this be Naomi?”
20 “Don’t call me Naomi,” she told them. “Call me Mara, because the Almighty has made my life very bitter. 21 I went away full, but the Lord has brought me back empty. Why call me Naomi? The Lord has afflicted me; the Almighty has brought misfortune upon me.”
22 So Naomi returned from Moab accompanied by Ruth the Moabite, her daughter-in-law, arriving in Bethlehem as the barley harvest was beginning.
3
An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth
generation shall they not enter into the congregation of the LORD for ever:
3
An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth
generation shall they not enter into the congregation of the LORD for ever:
3
An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth
generation shall they not enter into the congregation of the LORD for ever:
3
An Ammonite or Moabite shall not enter into the congregation of the LORD; even to their tenth
generation shall they not enter into the congregation of the LORD for ever: