Question
About a year ago, I bought an orchid for my mother as a birthday present. It was in full bloom and looked really good. The guy who sold it to me said that with proper care it should flower every year, but since then it hasn't flowered, although the plant seems to be doing well (its got more leaves, and it appears healthy). I'm not sure what type of orchid it is, except that it had white flowers, and is able to grow in a regular household environment (it diesn't need a hothouse, or special humid conditions or anything). How can I induce it to flower again?

Answer
My assumption is that your mother's plant is either a phalaenopsis or a dendrobium.  A phalaenopsis would have a single flower spike withy several large flowers.  The dendrobium would be cane-like and have several flower spikes with more but smaller flowers.

You didn't explain her growing conditions such a temperature, amount of light, etc.  My assumption is that she is growing under room temperatures (70 -80 degrees) year around and in an east, south or west window.  If that is the case, she might try switching to a "bloom booster" fertilizer (ie it has a high middle number such as 10/50/20).  That might be especially helpful if  she has been using a plant food with high nitrogen (eg 30/10/10).  The high nitrogen fertilizer causes the plant to put all of its energy into new growth rather than flowering.

Finally, most orchids prefer a day-night temperature differential of at least 10 degrees (ie 10 degrees cooler at night than during the day).  This is most easily achieved in the winter when the nights are much cooler and may be why most of the phalaenopsis naturally flower in late winter or spring.  The night temperature may go down to 60 degrees as a minimum for phalaenopsis.