Keywords are the search terms used to find your website in search engines. They are selected using Google keyword planner to rank websites higher in search results. They are implemented on the website meta tags and content to help increase the visibility of your domain in search engines.
Keywords are a way to get your target audience to get connected to your website. They help to drive organic traffic to your page.
Keywords if explained in a most general way we can say that they are search queries by using which a searcher reaches your site. Thus keywords are a bridge between the searcher as well as the webmaster. Not only this but search engines also require to match the relevancy of the web page to the search query by the searcher. But thinking only keywords will drive traffic to your page can be the biggest mistake to be made but that is a completely different thing to discuss.
Keywords can range from anywhere a single word to a complex phrase. Keywords are all based on your research and analysis as they can be found everywhere from the Heading of your page to the URL of your website. Keyword analysis helps you in increasing the On-Page optimization of your page. How? You will choose keywords in your content which are less competitive but at the same time have a fair amount of search volume thus giving you a better rank in SERPs.