When checking the click through rate & click rate in email performance, it is clearly explained as follows:
Click rate
Click rate is the percentage of people who clicked a link in your email out of the people who were delivered your email
Click through rate
The percentage of recipients who clicked a link in your email out of those who opened it.
However, in this post that I have just read "The Best Time to Send an Email (Research-Backed)" (https://blog.hubspot.com/marketing/best-time-to-send-email), it is said that "Click-through rate refers to the number of people who open a link or image in an email. This number will always be smaller than the open rate of emails opened due to the fact that it's calculated using the total number of emails sent." and "Click-to-open rate When comparing the number of people that opened your email and the number that clicked on any links, that data is called click-to-open rate".
This leads me to confusion, as I have aways understood that click-through rate was related to clicks vs opens, but in the post is related to clics vs delivered emails.
People use terms like these inconsistently and interchangeably, and there is no universal definition, so your confusion is well justified.
While I typically trust HubSpot's research and findings, that article is especially unhelpful since it confuses the absolute number of clicks with the click-through rate, which should be expressed as a ratio. It also states that a click-through includes opening an image - which is plain wrong unless opening it equates to clicking on tracked link to hosted version or url.
The important thing is that you use your interpretations of these consistently.
Since you use HubSpot, I would stick with the definitions provided in the tool.
People use terms like these inconsistently and interchangeably, and there is no universal definition, so your confusion is well justified.
While I typically trust HubSpot's research and findings, that article is especially unhelpful since it confuses the absolute number of clicks with the click-through rate, which should be expressed as a ratio. It also states that a click-through includes opening an image - which is plain wrong unless opening it equates to clicking on tracked link to hosted version or url.
The important thing is that you use your interpretations of these consistently.
Since you use HubSpot, I would stick with the definitions provided in the tool.