Welcome to the matrix

Matrix management, that is.

As a product manager, you have access to resources - engineers of multiple disciplines, UI/UX designers, the list will vary from organization to another but the fact remains, you directly affect the work and priorities of a good number of people; yet, you are not their boss, you are the product manager.

This position may sound somewhat confusing at first, but it can be an awesome place to be in. The working relationships you will form can be free of tensions and anxieties people often feel towards their direct manager, thus allowing for a more creative, team-spirit environment. Cooperation is formed around mutual goals rather than forced by authority.

You may ask, how can I properly influence without direct, formal authority? I expect the answer to that one will vary from one PM to another, my personal answer - through leadership, passion and earnestness. I firmly believe that a PM's level of dedication is strongly felt by their coworkers, it generates drive and strengthens accountability.

A product manager is not only the product owner, he also takes ownership of the vision that brought this product from idea to actual work in progress. He/her must believe in that vision, champion it, and make sure that the various team members working on it are aligned with the immediate tasks at the least, if not with the full blown product goal (some people function better when their work is compartmentalized - you can't fight it, try to make the most of it).

To summarize, you must remember that you are meant to lead, regardless of titles and authority. Set goals that you believe in, get the right data to prove and justify these goals, and make sure to properly onboard and involve the project team.

If your team members fully understand the product's goals, and have a sense of partnership in achieving them, you are at an excellent starting point. Show them you care about your product, care about them fulfilling their parts in it, and care for them as people... those are the traits of a leader, if you show them they will follow.