Though you use them every day, you may not give much actual thought to words. The fact is that most people do not pay attention to the words that they see and hear, nor the ones they use. However, words are an integral part of the world and communication. Without words, either spoken, written or hand-signed, our ability to evolve would be drastically diminished.
Words are simply combinations of sounds that have developed meaning. For those living within the same society, they will use and understand the same words though they may be perplexed or even entirely lost when traveling to a region with vastly different words. Though the strict definition of words only includes vocalized and written transmissions, for those who are in the deaf community, the words of sign language are equally meaningful.
Without words, we would be limited to body language and facial expressions to let others know our feelings about a particular matter. These actions could not be accompanied by any type of vocalization, because that sound, if repeated, would be considered a word in that situation. Language is highly adaptive and can grow, change or even sprout up due to environmental circumstances.
Take the case of twins, triplets and other multiple births. While particularly with twins, it is also common with babies born at the same time to develop their own language during the early years. Because their twin is likely the person with whom they spend the most time, and is at the same stage of development, they are learning about the same things together. Although they have adults, and possibly siblings or other kids, around them speaking on a regular basis, these older people form words that the youngsters cannot.
The two, or more, may begin to speak their own utterances that the other understands. Oftentimes, the adults around them cannot make sense of these vocalizations because they are based on something between the kids, and not necessarily anything the rest of the world even knows about. If the twins have a sibling that is not too much older than them, it is possible that the youngster will be able to understand the language of the twins and convey their thoughts to the parents when necessary.
The many different languages across the world can be traced back to a few original tongues. From these, as people moved into various locations and had reduced contact with others, the words spoken would evolve over time. This has happened to all of the original root languages and is still taking place today.
If you speak English, consider all of the variations in what you hear that are considered the same language. Not only do the people in Britain and Canada sound different and use unfamiliar words to the American ear, even within the country regional differences can leave some confused during a conversation.
The history and continual changing of words are truly fascinating. As you continue to explore, notice the fluctuations in the words you see and hear in your life.