Committing to a college is an incredible accomplishment and it should be celebrated. With that said, understanding the difference between a verbal and signed commitment is very important
You can verbally commit to a college at any time during high school but it's non-binding for both you and the school, meaning that you haven't signed or can't sign with that college yet. The only time your commitment is binding is when you sign a commitment accompanied by some sort of financial aid agreement.
You can change your verbal commitment at any time during the recruiting process, but be sure you communicate your intentions with the college program you have committed to. Furthermore, changing your commitment frequently can leave a bad taste in the mouths of college coaches and can certainly burn bridges.
There are a couple of different names for signed commitments depending on which schools you're committing to and their respective competition level.
For NCAA DI and DII programs, you sign a National Letter of Intent (NLI) which is a binding agreement between you and that college. An NLI states that:
You are agreeing to attend that school full-time for 1 academic year
Your school agrees to provide athletic aid for 1 academic year
For NCAA DIII schools, there are no athletic scholarships and, therefore, you don't sign an NLI. In 2015, NCAA DIII programs began to offer a type of "celebratory NLI" for student-athletes to sign. Instead of athletic scholarships, NCAA DIII schools offer academic scholarships.
With regards to NAIA programs, student-athletes sign a Letter of Intent (LOI), which operates very similarly to NCAA NLI's.
Before you sign with a college program and post your decision on social media, reach out personally to each college coach who recruited you along the way to thank them for their time and to inform them about your decision. This is a thoughtful gesture that is appreciated by college coaches.