Does this site cost anything to use?

Nope. It’s completely free and always will be.

How do you give money to charity if it's free to use?

For every purchase made that starts with a link on our site, Leave a Trace gets paid a commission. The commission comes from the partner that was bought from (e.g., Expedia), not from the customer. Those commissions are what gets donated.
For this month and the foreseeable future, 100% of commissions will get donated. At some point, it may prove necessary to use a small portion of the commissions to fund our site’s operations, but we will clearly explain that decision if it ever comes.

How much will my purchase give to charity?

There are some exceptions, but the below guidelines are good approximations of how much each type of purchase gives to charity.
Hotels: 4-6% of the booking amount

Cars: 2% of the booking amount

Flights: $3-4, regardless of ticket price

How do you pick which charities to give to?

Each month, we go through a process to pick our charities.
Step 1-Booking trips and making purchases (throughout month): Throughout each month we’ll be hoping for as many sales as possible. Those sales generate commissions (which we discussed here). The more we generate in commissions, the more we can donate to charity. On the first day of the following month, we’ll post a list of the countries our users visited and the commissions that were generated by trips in each.

Step 2-Charity nomination (first week of following month): For the next week, anyone can propose charities which operate in the countries we visited.

Step 3-Charity selection (second week of following month): For the following week, a poll will be open on this blog to vote on the charity we most want to support.

Step 4-Donation (15th of following month): We’ll finalize the donation to the winning charity (and post a picture of the check here).

As an example:

Until Feb 28 all bookings and purchases count towards February’s total
Mar 1-7 we’ll be asking for charity nominations for the February commissions
Mar 8-14 we’ll be conducting our first poll
Mar 15 we’ll make our first donation