Keyword Research, when discussed in the context of Search Engine Optimisation (SEO) or general marketing strategies, is the process of understanding how your target market searches for your services and content that you syndicate.
By understanding what keywords are used, you can show up in search results more effectively, in turn creating more traffic, and increased conversions.
There are two types of keywords, with the first being short-tail keywords. Short-tail keywords only contain the keywords of the subject and typically are less successful than long-tail keywords, which are generally made up of 3-5 words and are more specific
Long-tail keywords tend to generate less search traffic than short-tail keywords, however long-tail keywords have a much higher conversion rate, as you are targeting a very specific term that the user is searching for.