There are six main tiers with Intel's CPU's: Pentium - Pentiums are dual core processors without Intel's hyper-threading technology. They aren't very powerful but are cheaper and useful for HTPC's or basic workstations. i3 - i3's are dual core processors that do have hyper-threading, this means that they have 4 executable threads, so they perform comparably to a quad core for cheaper. i5 - i5's are quad core CPU's without hyper-threading. They are currently the most popular CPU for high end gaming as the performance benefit of an i7 is negligible and not worth the price increase for many people. i7 - i7's are quad cores that do have hyper-threading so have an effective 8 threads that can be utilised, this makes them great at parallel tasks such as video rendering, but doesn't assist gaming much. i7 Extreme - The top CPU's that Intel make. These are quad or hexa core processors that have hyper-threading enabled, they are prohibitively expensive however. Generally marked by an "X" at the end. Ex: i7-5960x Xeon - Intel's workstation CPU's, I mention them because some of the lower end Xeon's are effectively i7's without integrated graphics and a much cheaper price. There are different classifications based on time of creation. Note: If it is followed by "k" ie: i7-4790k then it is unlocked and can be overclocked easily. Overclocking is changing the clock speed of which the processor runs in an attempt of raising the performance of the processor at the expense of electricity + heat. The newer generations have lower heat output and power usage. (On average, there are some exceptions) 9xx - Generation 1 | Codename "Bloomfield/Gulftown" | Quarter 4 of 2008 | Gulftown has smaller microarchitecture of the transistors at 32 nanometers. Ex: i7-875k (the 800x series is also part of Generation 1. It's codename is "Lynnfield" 2xxx - Generation 2 | Codename: "Sandy Bridge" | 2011 Ex: i7-2600 3xxx - Generation 3 | Codename: "Ivy Bridge" | 2012 Ex: i5-3570k 4xxx - Generation 4 | Codename: "Haswell/Haswell Refresh" | 2013-2014 Ex (Haswell): i7-4770k Ex (Refresh): i7-4790k 5xxx - Generation 4 | Codename: "Haswell E / Haswell Refresh" | 2014-2015 The latest series released. Still in the haswell architecture but has lower price/performance ratios. Has much better TMI which allows for higher overclocking headroom (Thank you /u/k1ngm1nu5[1] ) Ex: i7-5960x Note: I will not list any Intel Xeon processors since I don't know enough about them :) Edit: changed "17-5960x to "i7-5960x" Edit 2: Clarified "9xx" as Generation 1 Edit 3: Won't be doing an AMD portion since I don't use/have not used it before. I may do one after research but I don't really have motivation to do one. Edit 4: Thanks /u/JaffaCakes6[2] for the "Haswell Refresh" clarification/mishap fix! Completely necessary gold edit: Thank you so much anonymous! It's so shiny! (Just like the pins on my CPU <3)