Technically speaking, a landing page is any page that a visitor to a website arrives on. Historically, that was usually the homepage if the visitor found you through a web search, or occasionally a specific page if they were searching for something in particular. However, social media and digital marketing have radically altered the concept of a landing page.
Landing pages typically are single-serving bits of content that tell a story to persuade visitors to complete an objective. Landing pages are used for product launches, sales announcements and contests, among many other uses.
Outside of a digital marketing context, many people refer to landing pages with their traditional meaning -- the page that a visitor lands on at your site. Because of social media, visitors to your site rarely come to the home page. In fact, many designers and publishers believe that we're witnessing the death of the home page as the focal point of a website. On social media, people link to whatever page has the content that they're interested in - sometimes that's a page of your site that features a video, sometimes it's an article - all pages are landing pages now, and all pages should be treated with care. The days that business owners can focus on having a well-designed homepage with merely adequate supporting pages have long gone. Every page of your site should be treated as though it may be the first page a visitor to your site sees.
Digital marketers have co-opted the landing page as one of the main tools to be utilized in digital marketing. Landing pages are either custom coded or built using a variety of free and paid tools (the best tools will set you back a bit of money). The modern landing page is designed with a specific purpose in mind. Everything about the page is designed, optimized, tested and iterated to make that one objective happen.
There are landing pages designed to convert visitors to any number of objectives. A landing page designed to solicit opt-in email addresses is known as a Squeeze Page. An email list is like gold to many businesses online, so a lot of effort goes into building the best landing page to grow your email list.
If you're seeking to grow your email list, you can make the focus of your landing page a bid to tell a persuasive story to your visitor. Tell them why they should give you their email address. If you're a restaurant, consider employing an email drip campaign where you will send out 4 emails, teaching new subscribers how to prepare a full meal using recipes from items on your menu. Frame it as an online cooking course. Anything that will add value to their decision to hand you their email list.
Once you've got your landing page deployed the real fun starts. What you want to do is understand as much as you can about your web page. That means you have to dig into the analytics of your site. If you don't know anything about Google Analytics, it's time to get educated. Visit Google to learn more (https://support.google.com/analytics/answer/4553001?hl=en).
You want to know how the people using your site are using it. What is the bounce rate? That's how quickly people leave your site after they arrive. If they're leaving too quickly, you can be sure that they're not persuaded by your landing page. It's time to experiment. Change the copy, change the design, iterate and process the knowledge that you gain by analyzing the behavior of your site's visitors until you push the bounce rate down.
This is the same process you will use to optimize every aspect of your landing page. Maybe people are staying on your site longer, giving you some impression that they like what you're telling them, but perhaps they scroll down to a certain part of your site and leave. You can investigate this problem by analyzing the scroll depth of your landing page using a tool like this one ( http://scrolldepth.parsnip.io/ ).
Optimizing the design of your landing page to accomplish your objective would make it possible for you to take the same piece of content or same offer that failed to convert and dress it up in a way such that your customers will understand the value.
Any page where you want the user to take an action should be optimized this way. For instance, if you want the user to make a reservation to your restaurant, or buy your cookbook, or download your app, or whatever it may be, you can use these methods to improve those conversions.
You can do all of this yourself, but there are a number of services out there that are built to help you customize existing landing page templates that are already proven to convert very highly.
Services like Lead Pages and Unbounce offer a range of options suitable for just about any marketing needs. The benefit of using tools like these is the amount of testing that they have already undergone. Even after all of the extensive iteration that has been done to make their landing pages convert as highly possible, they still offer tools to allow you to conduct your own A/B testing to try out different copy, different images, different designs, in order to attain the right mix to get your customers to convert.