Polish, Czech, Slav... similarities?

Good evening.

Purely as a hobby, i've decided that i'd like to pick up a European language (I already speak a couple Asian languages).
I initially wanted to learn Czech, but i was comparing populations that speak languages in Europe and found that Polish outnumbers it and that it also has a lot in common with slavic languages.

tl;dr:  Anyone who speaks Polish or Czech, or any combination of those Slav languages, are there similarities?  'ppreciate your comments.

>>40
wat

You'd best be trolling, son.

Swedish is a well-established Northern Germanic language, related most closely to Danish, and more distantly to Norwegian, Icelandic, and Faroese, and even more distantly to Eastern Germanic languages like English, Dutch, and German.

Finno-Urgic languages include Suomi (Finnish), Magyar (Hungarian), and Saami.