When people talk about RAM, they’re usually talking about Synchronous Dynamic RAM (SDRAM). SDRAM is what this article discusses, too. For most desktops and laptops, RAM appears as a stick that you can insert into the motherboard.
Unfortunately, there is a rising trend for super thin and light laptops to have the RAM soldered to the motherboard directly in the interest of saving space. However, this sacrifices upgradability and repairability.
Do not confuse SDRAM with SRAM, which stands for Static RAM. Static RAM is the memory used for CPU caches, among other things. It is much faster but also limited in its capacity, making it unsuitable as a replacement for SDRAM. It is highly unlikely you will encounter SRAM in general usage, so it is not something you should worry about.