Answer
In Hebrew, halakhah means “the path that one walks,” and the writings that comprise halakhah refer to just that. The halakhah includes the laws (mitzvah) found in the Torah (mitzvoth dˈoraita), rabbinical law (mitzvoth dˈrabbanan), and revered tradition (minhag). In Judaism these writings provide the path for one to walk.
The most sacred of the halakhah are the 613 commandments from the Torah (the first five books of the Bible). They include the Ten Commandments as well as the ceremonial and civil laws. The rabbinical halakhah include laws created by past rabbis to prevent people from breaking a law from the Torah; for example, some of the rabbinical laws provide specifics on what is and is not allowed to be done on the Sabbath. Rabbinical halakhah also includes rules governing the celebration of extra-biblical holidays such as Chanukkah. Minhagim are long-held customs whose source was expediency and not theology. Minhagim include the liturgies that have become customary in the various communities of Jews.
Although Judaism says all the laws should be followed, there is a hierarchy. Laws from the Torah take precedence over rabbinical laws and customs. Laws from the Torah are to be followed strictly, whereas rabbinical law can allow for more leniency. And a minhag, although part of the halakhah, varies depending on sect, geography, and time period.
The purpose of halakhah is to include worship of and obedience to God in everyday actions. It is part of the way Jews are set apart. Unfortunately, it’s not completely biblical. God gave the Torah, but the rest of the halakhah is man-made. Although Jewish custom says He also gave Moses the oral law to expound on the written Torah, there’s no indication in the Bible that this is so. Then to add interpretations and clarifications—not to mention extra-scriptural customs—it’s exactly what Jesus was talking about when He lamented the heavy yoke of the Pharisees (Matthew 23:3–5). Jesus never broke the Law of God, but He often violated man-made rules, and that was one reason the Pharisees despised Him so (see Mark 7:5–13).
Jews today generally view the halakhah as a guideline, but most don’t try to follow it religiously. Christians, of course, are not under the Jewish Law, and we have no responsibility to the wider halakhah.