Interspecific hybridization refers to the crossing of individuals from two different species to produce a hybrid. It is an important technique used in plant and animal breeding to introduce new traits or characteristics into a species. This process involves the combination of genetic material from two species that are closely related but distinct.

Explanation:

1. Interspecific hybridization:
- Interspecific hybridization is the crossing of individuals from two different species.
- It involves the transfer of genetic material from one species to another.
- The resulting hybrid has a combination of traits from both parent species.
- This technique is commonly used in agriculture and horticulture to produce new varieties with desired traits.
- For example, crossing a lion and a tiger produces a hybrid called a liger.

2. Intervarietal hybridization:
- Intervarietal hybridization refers to the crossing of individuals from different varieties within the same species.
- It is used to produce hybrids with improved traits or characteristics.
- For example, crossing two different varieties of roses to obtain a new variety with a unique color or fragrance.

3. Intergeneric hybridization:
- Intergeneric hybridization involves crossing individuals from different genera, which are higher taxonomic ranks than species.
- It is a more complex process than interspecific hybridization as the genetic distance between genera is greater.
- This technique is used to introduce new traits into a species that are not available within its own genus.
- For example, crossing a horse and a donkey produces a hybrid called a mule.

4. Intravarietal hybridization:
- Intravarietal hybridization refers to the crossing of individuals within the same variety of a species.
- It is used to produce hybrids with improved traits or characteristics within a specific variety.
- For example, crossing two different types of tomatoes to obtain a hybrid with increased disease resistance or larger fruit size.

In conclusion, crossing individuals of two different species to produce a hybrid is called interspecific hybridization. It is an important technique in breeding to introduce new traits and characteristics into a species. Other types of hybridization include intervarietal, intergeneric, and intravarietal hybridization, which involve crossing individuals within the same variety, genus, or species.