Assent refers to agreement, while an ascent is a climb. Before we make our way to the top of Mount Everest, we need to make sure our guide assents to our ascent.

An ascent is a physical climb up something, like your ascent up a rock wall at the gym. This word can also be used with reference to something less tangible, like an ascent up the corporate ladder. Ascents are for rockets and rock stars. Here are some examples:

Suddenly the temperatures plummeted as we began an ascent into mist-wrapped mountains, a conifer-clad peak thrusting its nose into the clouds. (Washington Post)

It was there he caught Fairchild’s eye and started his ascent up the corporate ranks. (Los Angeles Times)

Assent is a rather formal way to say "agree." If your parents assent to having your best friend stay for the weekend, go ahead and get the extra bed ready. As a noun, assent refers to an agreement. Here are some examples:

What happens if a consumer with one of these devices declines to assent to a revised privacy agreement? (Wall Street Journal)

Matt assented to the trip readily, and Jethro, with the letter in his pocket, drove off down the road, his heart pounding with excitement. (Across Five Aprils)

Here's a handy trick to remember the difference between these homophones: ascent has a c for "climb," while assent has those two agreeable s’s in the middle.