The thing about gender is that it gets everywhere. Especially when you're not thinking about it, people tend to fall back on patterns of behavior — it just makes things go quicker. Unfortunately, it also has a habit of calcifying the very practices that have saddled us with bias, the glass ceiling, and other gender-related inequities.
FastCompany reports on a study from Stanford University about divisions in how we parcel out praise on the job. Most of it is pretty nondescript: "You were a real asset to the team," "You had a great year," that sort of thing. What's not generic is how it's doled out — men received much more specific and amped-up compliments 57 percent of the time, while women are only praised like this 43 percent of the time.
This matters, and not just because it's nice to know that your supervisors are actually paying attention to your labor. Women are less likely to be seen as "brilliant," which is a problem when women also have trouble (through no fault of their own) breaking into top leadership positions and gaining support to progress in their careers. There are ways to update performance reviews so that they reward the right people, but women will definitely notice disparities in reward and treatment before HR will.
Make sure what you're noticing women for isn't gendered either: Office "housework" and other thankless tasks often fall to women, and "feminine" traits aren't often valued when it's promotion time. Read FastCompany's full article for more suggestions on praising good work wherever you see it, in the fairest way possible.