Key performance indicators (KPIs) are the metrics businesses use to measure their performance. Using KPIs should give businesses a good indicator of whether they are performing well or poorly. This sounds straight forward but if companies are not using appropriate KPIs there company may be faring a lot better or a lot worse than what they think.
Good KPIs will measure the performance of an outcome acceptable to the business. If your business wants to increase brand awareness, for example, a KPI to examine would be impressions of video ads or social profile views. KPIs can change with the way your business grows, it is important to keep them up-to-date and in line with the goals and developments of the business.
Furthermore, different KPIs will apply to different campaigns and strategies. Your company does not need to rely on one KPI at a time, in fact you could be digging yourself into the ground if you do rely on just one KPI. The complexities and multi-dimensions of companies cannot usually be diluted to one KPI. And KPIs definitely do not need to be solely focussed on revenue. There are many ways a business can be performing well that do not have a monetary value, think of newsletter sign ups, phone calls, page-likes, etc.

Worse than having irrelevant KPIs is not having any at all. You will be doing yourself a disservice by not using KPIs to understand the performance of your company. Reviewing KPIs can give you quick but insightful information on your past and current performance which can then guide future strategies.
Good KPIs will take into account your current performance and direct future performance. Taking the time to determine which KPIs are relevant to your company and what you want to achieve will help keep your business and strategies on track.