A Mitzvah, is a Hebrew word which means "commandment" and "connection."
The Mitzvahs are, 613 of, G-d's commandments to the Jewish people.
Mitzvohs are the ultimate expression of our relationship with G-d. There's no set place and time that's just for G-d, every place and time can shout out "G-d!" And that's the idea of the Mitzvah. For "Mitzvah" doesn't just mean "commandment": it also means "connection". You are connected to G-d.
When you do a Mitzvah, you're expressing that connection.
There are 248 positive mitzvohs and 365 negative mitzvohs.
They can also be divided into Ethical and Ritual categories: Ethical Mitzvahs tells us how to interact with fellow humans, such as not taking revenge or hurting orphans, and Ritual Mitzvahs teach us how to interact with G-d, such as keeping Shabbat or building a Sukkah.
The Torah decides what is ethical, not our conscience. So ethical Mitzvahs are often difficult to observe, because violating them is easy to rationalize. But observe them we must, for they carry just as much weight as any other Mitzvah. And to observe them of course, (solely) because G-d commanded us to - and we want to be connected to Him.
Have a blessed day.