Perhaps you are one of those wonderfully geeky souls who learned to use wiki markup & still enjoy the opportunity to practice it whenever the opportunity presents. If so, you are in luck -- Wikipedia (& sister projects) still support wiki markup by default.
But -- perhaps instead you remember wiki markup as a complicated and frustrating barrier to easy participation in Wikipedia. Or perhaps you have no idea what "wiki markup" means. If this is the case, you are also in luck because Wikipedia now supports a Visual Editor which functions pretty much like any other modern text editor on the internet today.
Wikipedia's Visual Editor is not enabled by default but it's very easy to make it your default text editor. Here's how to do it:
NOTE: the Visual Editor is a bit fussy about browsers. Chrome & Microsoft Edge are usually just fine but sometimes Firefox is problematic.
Want more information about the Visual Editor? Or would you like a chance to "try before you buy"? This page: Visual Editor User Guide provides both.