Whether you're planning a business trip or a family vacation there are plenty of ways to save by making your reservations online. Websites like Expedia (NASDAQ: EXPE), Priceline (NASDAQ: PCLN) and Orbitz (NYSE: OWW) can help you save money when you book everything from airfare to rental cars. There are also lesser-known (but just as effective) websites like Ctrip.com International (NASDAQ:CTRP) and MakeMyTrip Limited (NASDAQ: MMYT) that focus on discounted international travel. In fact, there are so many different websites devoted to helping you save money while you travel that it can be difficult to know which one to use to get the best deal.

Expedia.com

Expedia is one of the largest online travel agencies (OTAs) in the world. You can book flights, hotels, cruises, cars and even complete vacation packages through them. Expedia negotiates discounts with most of the major airlines (excluding Southwest (NYSE: LUV)) and over 750,000 hotels. A single search on Expedia returns the top results for all of them.  They also offer a rewards program for their repeat customers called Expedia+ Rewards which allows you to earn points for every dollar you spend booking with them.

Priceline.com

Priceline's "Name your Own Price" bidding system really sets it apart from the competition, but it is a blind booking process. You select the dates you want to travel and enter the amount you are willing to pay. Priceline takes your offer and compares it to a list of available flights and hotels. You never know which airline you might be flying on or which hotel you will be staying at until after your credit card is charged. Also, according to Priceline's FAQ, " All Priceline tickets are non-refundable, non-changeable and non-endorsable" so be sure you're ready to commit before you hit submit. If you're ok with a bit of uncertainty in your travel plans you can often find deeply discounted hotel room rates by using Priceline's website or mobile app. (For more, see: How Do Hotel Night Auctions Work?)

Orbitz.com

Orbitz offers the best price guarantee among the top OTA's. If you book through their service and then find a better price somewhere else they will award you one hundred percent of the price difference as a credit along with an additional $50 credit. The credits come in the form of Orbucks, the Orbitz reward program currency. Orbitz rewards members who have reached silver, gold and platinum status can get additional credits by using their best price guarantee, up to $200 extra each time a lower price is found. (For more, see: Expedia vs. Orbitz: Comparing the Rewards).

International Travel

If you're planning to travel internationally you may want to step off the beaten path a bit and investigate some websites that focus entirely on international travel deals. CTrip.com for example, is the leading OTA for travel to China. They offer vacation and tour bookings along with discounted flights, hotels and train tickets. Similarly, Make My Trip can help you book flights and hotels to India at a discount.

The Bottom Line

Using an online travel agency to book your vacation can be a seductive and comforting process: simply point, click, search, purchase...done! However easy the process may be, remember that it does not always result in the lowest possible price. Airfare in particular can often be cheaper if you book directly from the airline rather than using an intermediary. By choosing to book with an OTA you may also be forgoing loyalty points for hotel chains like the HHonors program or even some of your credit card reward perks. (For more, see: Drawbacks Of Travel Reward Programs). 

Be sure to do your research before booking anything at all. Search all of the major OTA's to compare prices before you book and spend some time reading the fine print at each. What will happen if you need to change your plans? What if your flight is canceled? Discounted travel is a beautiful thing as long as it doesn't result in a costly headache if something goes wrong. For the full scoop on discounted travel check out how to Save On Planes, Trains And Automobiles.