Every written work should be proofread before it reaches its intended audience. Usually, you are the first person who must do your own proof reading. Unfortunately, you've been through the forest so many times your mind's eye, overlooks  out of place trees as part of the scenery due to your familiarity. Others, going through your forest of words and worn pathways will see things that you don't. This is why outside proof reading is very important to ensure your creation is well received and easy to read. TEP will provide the extra pair of eyes and experience  to spot the grammar and or spelling mistakes