Checking for spelling, grammar, and general readability issues is often called proofreading. It is important to proofread professional documents, letters, articles to catch errors before they're published. Some companies even employ people specifically for proofreading.
Computers can aid in proofreading as well. Many word processing applications, like Microsoft Word, have a built-in spelling and grammar check to alert the user to errors in their documents. However, these applications are not foolproof and may fail to detect certain errors. Therefore, it is still important to read over your work when it is finished.