When it comes to describing the importance of something, the phrase "essential to" is often used. However, there are a variety of synonyms that can be used to convey the same idea. For instance, one could say that something is indispensable, crucial, critical, vital, or necessary. Other synonyms for "essential to" include pivotal, central, fundamental, key, or integral. These words all describe the idea of something being absolutely necessary or vital to the success or function of something else. By choosing different synonyms for "essential to," a person can add variety and emphasis to their writing or speaking.