Right click on Layer you want to Rasterize and choose Rasterize Layer, or type. You can do the same thing from Layer - Rasterize and choose option.

The process of converting mathematical equations into onscreen pixels

Absolutely - there's a couple of ways to do it.

1. Export the file to a BMP or PSD format (File>Export)

2. For Objects on the artboard, select and then click on Object>Rasterize.

Only when you want to apply filter from Filter menu, my advice is instead of rasterizing through Rasterize command to convert Type layer to Smart Object which gives you ability to change settings for applied filter and keeps editable text so you can change and text: font, size, kerning...

Adobe Illustrator creates graphics that are vector based and it deals well with text. It also has the ability to rasterize graphics and create PDF files.