ISTJ stands for Introverted, Sensing, Thinking, and Judging. It is one of the sixteen personality types identified by the Myers-Briggs Type Indicator (MBTI). Here is a detailed description of the ISTJ personality traits:

1. Introverted (I): ISTJs are primarily focused inward and gain energy from spending time alone. They tend to be reserved and prefer to think before speaking. They may appear quiet and reflective, needing time alone to recharge.

2. Sensing (S): ISTJs rely on their senses and pay attention to concrete details and facts. They are observant and practical, focusing on what is happening in the present moment rather than speculating about the future. They have a strong preference for dealing with reality and what is tangible.

3. Thinking (T): ISTJs make decisions based on logical analysis rather than emotions. They value objectivity and fairness, seeking to understand the underlying principles and systems. They tend to be straightforward and direct in their communication, often prioritizing facts and data over personal feelings.

4. Judging (J): ISTJs prefer structure, order, and organization. They like to plan and make decisions in advance, sticking to schedules and deadlines. They are reliable, responsible, and committed to fulfilling their obligations. They value stability and prefer to work within established rules and guidelines.

Additional ISTJ traits:

5. Detail-oriented: ISTJs have a keen eye for details and are meticulous in their work. They focus on accuracy and precision, ensuring that tasks are completed thoroughly and correctly.

6. Practical and realistic: ISTJs have a practical approach to life and tend to be grounded in reality. They prefer to deal with what is tangible and proven rather than abstract concepts or theories.

7. Dependable and responsible: ISTJs are known for their reliability and sense of duty. They take their commitments seriously and can be counted on to follow through on their promises. They are often seen as trustworthy and responsible individuals.

8. Organized and structured: ISTJs thrive in environments that are well-organized and structured. They prefer clear guidelines and procedures, and they excel at creating systems and routines to increase efficiency.

9. Reserved and private: ISTJs are typically private individuals who prefer to keep their thoughts and feelings to themselves. They may take time to open up to others and prefer to maintain a small circle of close friends.

10. Loyal and dedicated: ISTJs are loyal to their commitments and relationships. They value long-term stability and are dedicated to supporting and caring for their loved ones.

It's important to note that while these traits are commonly associated with ISTJs, individuals may vary in the degree to which they exhibit them. People are complex and can display a range of behaviors and characteristics beyond their personality type.