Description meta tags are important because Google might use them as snippets for your pages. Note that we say "might" because Google may choose to use a relevant section of your page's visible text if it does a good job of matching up with a user's query. Adding description meta tags to each of your pages is always a good practice in case Google cannot find a good selection of text to use in the snippet. The Webmaster Central Blog has informative posts on improving snippets with better description meta tags18 and better snippets for your users19. We also have a handy Help Center article on how to create good titles and snippets20.
A Coursera Specialization is a series of courses that helps you master a skill. To begin, enroll in the Specialization directly, or review its courses and choose the one you'd like to start with. When you subscribe to a course that is part of a Specialization, you’re automatically subscribed to the full Specialization. It’s okay to complete just one course — you can pause your learning or end your subscription at any time. Visit your learner dashboard to track your course enrollments and your progress.