Booking Aggregator site• Aggregators are handy tools that pack a lot of travel search engine punch. Rather than trying to find travel search engine sites and then leaping from one to another, use an aggregator, like Kayak, to search for discount airfare, hotel, car, packages and even cruise prices.
SEM• Search engine marketing (SEM) is a form of internet marketing that involves the promotion of websites by increasing their visibility in search engine results pages (SERPs) through optimization (both on-page and off- page) as well as through advertising (paid placements, contextual advertising, and paid inclusions)
SEO• SEO stands for “search engine optimization.” It is the process of getting traffic from the “free,” “organic,” “editorial” or “natural” listings on search engines. All major search engines such asGoogle, Yahoo and Bing have such results, where web pages and other content such as videos or local listings are shown and ranked based on what the search engine considers most relevant to users.
Skyscanner• Skyscanner is a flight search engine that allows users to browse for flights via price and location. Additional tools such as fare graphs, allow users to compare flight prices of any given route over a month period, or the price of weekend flights from any given city.• The site is multilingual, offering flight searches in over 30 languages  including Chinese, Russian, Portuguese, Polish, Spanish and Japanese.• Skyscanner does not sell flights directly; instead, the site can be used to find the cheapest deal for a desired route after which users are automatically transferred to the airline or travel supplier’s website to make their booking directly.