What was the purpose of adding CERAMIC and Kevlar to some of the older frames?

[Hi I'm Ray]

I noticed some of the older frames had Ceramic in their compositions, some had Kevlar. What do they do?

I had two Wilson rackets with Kevlar and noticed both felt somewhat stiff and harsh but solid. The last frame I saw ceramic in is my Fischer Pro No.1 from yr 2000. I also bought an oldschool Dunlop racket with ceramic + kevlar in it and noticed both frames had a comfortable dampened feel to them.