Post-training refers to the things done to a LLM after pre-training to improve it's performance, such as supervised fine-tuning, RLHF, instruction tuning, etc. This is a critical step before releasing the LLM. Typically, this refers to things done by the company or group before releasing the LLM. (For an example of this usage, see the GPT-4 technical report.)

• Kumar et al 2025 - LLM Post-Training: A Deep Dive into Reasoning Large Language Models

• Alignment
• Instruction-Tuning
• RLHF