Certification points can be earned in two different ways, earned over time whether you are online or offline or earned actively through online participation. One point is earned every 2 hours passively, beginning as soon as the character is created. For non-premium members, you can gain up to 12 certs while offline (24 hours). Premium members can gain up to 48 certs while offline. In addition, points are earned at the rate of 1 point per 250 XP for actions in the game. The points are used to purchase certifications, infantry weapons and vehicle weapons, which range from 1 to 1000 .
There is no limit to the number of certification points you can earn, although you will no longer accumulate any if you have 10,000 unspent certification points (50,000 for people with membership).
In the original game, you were limited to 34 Certification Points which were spent at Certification Terminals at the Sanctuary or at friendly Bio-Labs to unlock access to various types of equipment, such as the Medical Applicator. Certifications also unlock access to vehicles such as the Basilisk or Advanced Mobile Station (AMS).
By spending your Certification points, this is how you begin to specialize your character. You could choose to play as a heavy soldier and grab the tougher armors and bigger guns but then you might be dependent upon getting transported to the battle by others that have chosen to specialize in piloting vehicles. Or you could choose to be an Advanced Combat Medic with the ability to revive fallen comrades on the field or an Advanced Hacker with the ability to quickly hack your way into an enemy base. The choices you made were not permanent as you could unlearn certifications and choose others in their place via the "Unlearn" feature in the certification terminal.