Microcopy refers to the small bits of text in the user interface that helps to guide or reassure users.
While designers often seek to avoid adding additional text to a screen, if that small bit of text helps the user move forward it is definitely worth adding. Use microcopy to alleviate fear, to add encouragement and to educate. Always think about users and what questions they might have. Those might be the same questions that cause them to drop off.
For example, in the picture above we use microcopy to reassure the user that they will not be charged if they click the button. Take out the microcopy and it might mean some users will not continue.
There are also occasions where users may have to provide some financial details to a company but are reluctant to do so. Again, microcopy can be used here to alleviate concerns.
In this example, user testing probably showed that users did not want to enter their phone number for fear of it being shared with third parties. If the phone number is required to complete the form, then users would quit at this point in the task flow. Adding the microcopy, “Your phone number is kept confidential and not shared with others” reassures users so that they can enter their phone number with confidence and continue through the flow.
Some designers will prefer less text on the screen because it looks better. However, to avoid the possibility of confusion, it is best to error on the side of including the text. More experienced users who do not need the instruction will skip it anyway. A simple rule of thumb is if the required action on any screen is not obvious, add a line of instructional text. Usability testing can help reveal whether an instruction is needed. If the vast majority of users can use the app without instruction, then you can leave it out.