Before discussing into deep, let us have a look at the basics.

1. ∅ = {}
2. ∅^* = ε
3. 1^*∅ = ∅
4. 0^* =  Zero or more occurence of 0 = {ε,0, 00, 00000, ........}
5. 0^*  1 0^*  = String containing exactly one 1 ={1 , 010, 01, 0001 ,....}
6. 0 1^* = Anystring which starts with 0 ={0,01, 0111, 01111 , .....}
7. ∅+R = R+ ∅ = R
8. ∅.R = R.∅ =  ∅
9. ε = {ε}
10. (R + ε) or (ε +R) != R
11. R. ε = ε.R = R
12. ε + RR^* = R*
13. Σ* = any combination of symbol . for example let Σ =(a,b), then Σ^* ={ε, a, b, ab, ba, aaab , abababa, abbbbb ,......}