Re-amping is a technique used to make an amp react to recorded guitar equipment the same way as it would react to a live guitar. Reasons to re-amp include convenience, budget, experimentation, and using it as a plan B. With re-amping, you can record your guitar using an amp simulator, and then re-amp at a later time. Re-amping is cheaper than renting a huge amp. You can experiment with different recording tool positions after you record, and if you position your mic incorrectly, you can always fix it with re-amping.
Read the full article here: