As a native English speaker, I first learned of "active voice" and "passive voice" when I started using tools to check (and correct) my writing.

In terms of sentence structure, "active voice" means the subject of the sentence performs an action; "passive voice," therefore, is somewhat the contrary: the verb acts upon the subject.

See https://www.grammarly.com/blog/active-vs-passive-voice/ for more.

(p.s. I do not work for grammarly and I am not promoting the app)

The is my favorite example of active vs passive:

First active

> I went to the woods because I wished to live deliberately, to front only the essential facts of nature, and see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.

Now passive:

> A decision was made to go to the woods because of a desire for a deliberate existence and for exposure to only the essential facts of life, and for possible instruction in its educational elements, and because of a concern that at the time of my death the absence of a meaningful prior experience would be apprehended.

https://theamericanscholar.org/writing-english-as-a-second-l...

In technical writing, which is often trying to be as concise as possible, active voice usually allows the shortest sentences, which, as a practice, tend to be more clear.

However, there are instances when the passive voice is important and should be used. For instance, if you are trying to put an emphasis on the fact that a subject receives an action. This can often be done in a passively voiced sentence where you clarify a certain relationship. In other words, passive voice can be an important part of adding context.

The idea that you should never use passive is largely just people hearing a rule and thinking it is the end all be all. In reality, you're better off learning what both types of structure do, and then choosing one or the other with a specific goal in mind.

The active voice removes the information about what agent is responsible for the action, which has the effect of removing clarity. The reader would like to understand cause-effect chains, whereas the passive sentences indicate that certain actions happen, as if spontaneously.

Passive sentences are used in blame-deflecting language, such as statements that superficially look like apologies, but don't indicate who is at fault, and so do not indicate any acceptance of responsibility.

Here's why you should use the active voice:

1. It lets you know who/what is performing the action, instead of leaving it to the reader to figure it out.

2. It makes the writing less repetitive because each descriptive word becomes a verb, instead of "to be" being in every sentence.

Personally I find active voice to be more repetitive as it tends toward a similar sentence structure of subject-verb and can also imply certainty in situations that are more nuanced. However, active voice and simple sentence structure should be used when possible to avoid redundant, flowery language.

Active voice is usually more clear, tight, and pleasant to read.

“We are raising your plan’s rates.”

versus:

“The plan’s rates have gone up.”