It is the ability of the system to undergo changes with a degree of ease. In simple words, how easily changes can be made into functionality to meet new business requirements.
Points to be considered:
- Industry standard coding standards.
- GoF and other design patterns.
- TDD or ATDD technique
- RESTful API standards.
- DDD patterns to solve complex domain.
- Anti-Corruption Layer (ACL) between modern and legacy system.