Kindness and acts of kindness have the potential to cause tremendously positive effects on subjective well-being, reflected in improvements in mental and physical health, and interpersonal relationships. Fostering knowledge about kindness may help in self-development and psychotherapeutic interventions aimed to improve an individual's emotional well-being. However, existing research data and understanding of this phenomenon in Russia, as well as descriptions of acts of kindness, are presently relatively limited. To study the Russian understanding of kindness, its meaning in the Russian context; to categorize a variety of identified acts of kindness; and to define kindness based on the data derived from a Russian sample. There were 291 Russian participants, recruited using an online recruiting platform, who filled out an online questionnaire that identified definitions of kindness with corresponding examples. Also captured in the sample were the participant's age, gender, and religiosity. The data underwent qualitative analysis through open, axial, and focused coding. As a result of qualitative analysis, four theme categories emerged to define kindness: a) personal states and qualities (one's own states and self-perception, moral values and qualities, self-regulation and emotional stability); b) openness to others (attention to others, love and positive attitude); c) emotional and cognitive understanding of others and tolerance, actions and behavior (altruistic sacrifice, help, politeness and respect, forgiveness, generosity, pleasing actions). Concrete examples of kind acts and behavior were categorized. A definition of kindness was formulated based on the data. The research results can be used in training, counselling, and therapeutic sessions to increase subjective well-being. Directions for further research have been defined.