What is the table 310.16 of the NEC?

It's a table that shows the ampacity ratings for the particular wire size and insulation you are using. Example: #12 THHN CU is rated @ 30amps under the 90 degree column. (#12)is the wire size, (THHN)is the type of insulation on the wire (CU)is copper. You shouldn't be using the chart unless you're a qualified electrician simply because there are many sub rules and exceptions.