A typical web or mobile development project would normally require the skills of a front-end developer and a back-end developer. But if the same person handles the responsibilities of both positions, they work on full-stack development. For a robust career in full-stack development, professionals should have specialization in at least one backend programming language. Aspiring full-stack developers may opt for PHP, JavaScript, Python, or Ruby on Rails initially. However, as they grow into their role, they can start working with more than one language. This will ensure that they stay relevant in the industry and build the capacity to take on more projects down the line.