How do we define this concept?

There are many different ways, but I would like to use some mekorot (sources) to explain it:

-  Shimon HaTzadik said: The world depends on three things for its existence, the study of Torah, the service of God, and acts of kindness - Avot 1:2.

-  These are the precepts that have no prescribed measure: leaving the corner of a field for the poor, bringing the first fruit offering to the Holy Temple, acts of kindness and Torah study. - Peah 1:1

-  These are the precepts whose fruits a person enjoys in this world but whose principle remains intact for him/her in the world to come...acts of kindness. - Talmud Bavly, Shabbat 127a.

-   The Jewish People are characterized by modesty, mercy and benevolence. - Talmud Bavli, Yevamot 79a.

-  Whoever is merciful to his fellow men is certainly of the children of our father Abraham. - Talmud Bavli, Beitzah 32b.

From these mekorot, we see that we can act in any way we consider proper in order to demonstrate our love of our fellow human beings.

In the remaining few days of the secular year, let's remember our sources, read them, and experience their words.