Each travel agency has its own website and its own special techniques to sell its products.
The most effective way for customers to filter product and service information to get what they want is:
Search Engines
Such as Google, Yahoo, or Bing on the internet.
Search engines have become essential tools in filtering massive information.
Thus said, travel agencies can now use techniques to make their websites popular and displayed in the top lists in search engines.
Search Engine Optimization (SEO)
Buying advertising spaces in search engines (Paid Search).