In case you've never seen one before, a word search is simply a grid of letters — in a square or rectangular shape — that contains hidden words. Your goal is to find and circle the words, which may appear horizontally, vertically, or diagonally within the grid. Some words may be written backward. Some word searches are constructed around a central theme, which means all the words you're finding are related to one topic.
How do you know what words to look for? The puzzle constructor usually provides a list. You may encounter word searches that don't provide a word list, in which case the puzzle constructor tells you how many words you're looking for (and whether they all relate to a certain theme). Those searches are more challenging, of course.
The puzzle constructor may let you know that the word search contains a hidden message (related to the theme, if the puzzle has one), which you discover only after circling all the words. To find the message, you identify, in order, all the letters you haven't circled. The letters form words that spell out the secret message.
Word searches are really low-stress. If a word list is provided, it's guaranteed that you can complete the search — no matter how large the grid or how many words you're looking for. How often in life do you get the satisfaction of knowing you're going to get the right answers? That fact makes working word searches fun. Plus, they're great for increasing your concentration and blocking out the world for a while.