Rav Avrohom Ben HaRambam says that the Rambam in Pirkei Avos says that all speech falls into one of five categories. Some categories are a mitzva others are an aveira. Some are permitted but should be limited as much as possible and others are not an aveira but considered reprehensible.The categories are as follows.
1. Metzuveh - speech that we are commanded. This includes torah learning.
2. Ne'esar - forbidden speech like Lashon Hara and Sheker, lies.
3. Ma'us - reprehensible. This include idle chatter. People of value try to refrain from this kind of talk as much as possible.
4. Ahuv - beloved speech. This includes praise of intellect and good character traits and putting down baseness and vulgarity. This is necessary as long as you say the right thing at the right time to the right person.
5. Mutar - permissible speech. This includes business dealings and other things tending to a person's basic needs. It is praiseworthy to limit this as much as possible.