"Estoy caminando" (I am using) is a Spanish compound verb in the present progressive tense. The first part of this compound verb is "estoy" (I am). The second part of this compound verb is the present participle "caminANDO" (walkING). In Spanish, the present progressive tense and the past progressive tense both use some form of "estar" as the first part of any compound verb. In addition, the present and past progressive tenses of Spanish, use "-ando" as the suffix that translates to "-ing."
"Estoy caminando" (I am using) es un verbo compuesto que está en el presente tiempo progresivo de español. La primera parte de este verbo compuesto es "estoy" (I am). La segunda parte de este verbo compuesto es el participio presente "caminando" (walking). En español, el tiempo presente progresivo y el tiempo progresivo pasado cada uno se usa alguna forma de la palabra "estar" como la primera parte del verbo compuesto. También, los tiempos progresivos presentes y pasados de español, usan "-ando" como el sufijo que se traduce como "-ing".
Yes, I guess it's quite complicated for someone who speaks English natively to know the difference between estoy and soy, once in English there's just the verb to be for both meaning. For me it's no big deal cause I'm Brazilian and Spanish and Brazilian Portuguese are very similar. Eu estou caminhando, yo estoy caminando, I'm walking.
"I like to write." means the same thing as "I like writing." both "to write" and "writing" in these sentences are used as if they were nouns. Yet there is a subtle nuance, as writing is something you are definitely doing, while "to write" is something that you could do. http://www.differencebetween.com/difference-between-gerund-and-vs-infinitive/
A gerund is always used as a noun in English and is formed from the present participle of a verb. "writing" when used as another part of speech is not called a gerund in English. So in English we say that the present progressive uses the conjugated present tense of the verb to be such as "I am..." + the present participle. "writing". Here in this sentence it is not being used as a noun. "I" am not the "writing".
An infinitive can be used as a noun, adjective or adverb.
The meaning of the sentence can change if you switch a gerund for an infinitive.
"I remembered to take my book to school." means that I remembered that I needed to take my book to school. (Aren't you proud of me? I remembered.)
"I remembered taking my book to school." means that Ï remembered actually taking my book to school. (I am sure that I brought it to school, maybe it is in my locker.)
Some verbs will require a preposition to use the gerund.
"I use a hairbrush to comb my hair."
"I use a hairbrush for combing my hair."
A gerund is used when the action is real or done.
"She practices playing those drums all the time."
"He finished fixing the car."
Infinitives are used when the action is general. It is not limited by time or tense. They are also used when the action is not real (not actually being done at this time) and for the future.
"I want to learn to fly a plane."
"I plan to cook that recipe when I get home tonight."
Only a gerund can be the object of a preposition and not an infinitive.
the verb in infinite is caminar = to walk, by taking away -ar you get the radical: camin-. To the radical you can put different endings and get different meanings or different persons acting in different times. If you want walking, the -ing corresponds to -ando (for verbs ending in -ar) that is:
caminando = walking.
to be walking = estar caminando-> I am walking = estoy caminando, you are walking = estás caminando ...
The -o is an ending for the first person singular acting in present time i.e camino = I walk, if you want to stress the I you can say: yo camino